JP2013085333A - Rotor and motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor which can suppress occurrence of magnetic saturation and to provide a motor equipped with the rotor.SOLUTION: A rotor 3 is constituted so that a plurality of magnets 23 of one magnetic pole are embedded in a rotor core 22 fixed to a rotary shaft 21 formed of a non-magnetic material to form a magnetic pole section 24, core magnetic pole sections 25 formed in the rotor core 22 are arranged between the magnets 23, and the core magnetic pole sections 25 function as the other magnetic pole. A small diameter section 21a is installed in a part where the rotor core 22 in the rotary shaft 21 is fixed, and a magnetic path augmenting body 41 formed of a magnetic material is arranged at an outer periphery of the small diameter section 21a.

Description

  The present invention relates to a rotor adopting a consequent pole type structure and a motor equipped with the same.

  Conventionally, in a motor, a magnet magnetic pole portion is formed by embedding a plurality of magnets of one magnetic pole in a circumferential direction in a rotor core fixed to a rotating shaft, and the core magnetic pole portion integrally formed with the core is provided between each magnet. There is known a rotor having a so-called contiguous pole type structure that is disposed with a gap and functions as the other magnetic pole (for example, Patent Document 1). Such a motor is advantageous in terms of resource saving, cost reduction, and the like because it is possible to reduce the number of magnets of the rotor to half while suppressing a decrease in performance.

JP 2004-201406 A

  By the way, in a rotor having a consequent pole type structure, the core magnetic pole portion functions as a magnetic pole different from the magnet provided in the rotor, but there is no magnetic flux forcing (induction) like the magnet. For this reason, the magnetic flux of the magnet easily flows to a portion other than the core magnetic pole portion in the rotor. For example, the magnetic flux may flow into the rotating shaft. Therefore, it is conceivable to reduce the leakage magnetic flux by configuring the rotating shaft of the rotor with a nonmagnetic material such as stainless steel.

  However, in the IPM (embedded magnet) type motor in which the magnet is embedded in the rotor core as in Patent Document 1 described above, when the rotation shaft is made of a nonmagnetic material, the radial direction on the inner peripheral side of the magnet in the rotor core Therefore, there is a possibility that the thickness of the magnetic path becomes thin and it is difficult to secure a sufficient magnetic path area through which the magnetic flux passes. As a result, magnetic saturation is likely to occur, and when trying to increase the effective magnetic flux, there is a problem that, for example, the rotor is enlarged.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotor capable of suppressing the occurrence of magnetic saturation and a motor including the same.

  In order to achieve the above object, according to the first aspect of the present invention, a magnet magnetic pole portion is formed by embedding a plurality of magnets of one magnetic pole in a circumferential direction in a rotor core fixed to a rotating shaft made of a nonmagnetic material. The rotor is configured such that core magnetic pole portions formed on the rotor core are respectively disposed between the magnets, and the core magnetic pole portion functions as the other magnetic pole, and the rotor core is fixed to the rotating shaft. The gist of the invention is that a small-diameter portion is provided at a portion to be provided, and a magnetic path augmenting means made of a magnetic material is provided on the outer periphery of the small-diameter portion.

  According to the above configuration, it is possible to sufficiently secure the magnetic path area on the inner peripheral side of the magnet in the rotor by the magnetic path increasing means provided in the small diameter portion. Therefore, the occurrence of magnetic saturation can be suppressed without increasing the size of the rotor, and the effective magnetic flux can be increased.

The gist of the invention described in claim 2 is that, in the rotor according to claim 1, the magnet has a rectangular cross section orthogonal to the axial direction of the rotating shaft.
According to the above configuration, since the magnet has a simple shape, for example, cost can be reduced. Further, if the magnet has a rectangular cross section, the magnetic path on the inner circumference side of the magnet in the rotor is likely to be narrow (the magnetic path area is small). The effect of providing means is great.

The invention according to claim 3 is characterized in that, in the rotor according to claim 1 or 2, a reinforcing rib extending in an axial direction of the rotating shaft is formed in the small diameter portion.
According to the above configuration, since the reinforcing rib is formed in the small diameter portion, it is possible to suppress a decrease in strength due to the provision of the small diameter portion on the rotating shaft.

  A fourth aspect of the present invention is the rotor according to the third aspect, wherein the reinforcing rib is provided so as to face a central portion in the circumferential direction of the magnet in a radial direction of the rotating shaft. .

  Here, the magnetic flux of the magnet returns to the magnet mainly through the core magnetic pole portions provided adjacent to both sides in the circumferential direction of the rotor core. For this reason, the magnetic flux density on the inner circumference side of the magnet in the rotor is high at both sides in the circumferential direction of the magnet, but is difficult to increase at the circumferential center portion of the magnet. Therefore, as in the above configuration, by providing the reinforcing rib so as to face the circumferential central portion of the magnet in the radial direction of the rotating shaft, the strength of the rotating shaft is ensured while suitably suppressing the occurrence of magnetic saturation. be able to.

The gist of the invention described in claim 5 is a motor including the rotor according to any one of claims 1 to 4.
According to the above configuration, since the effective magnetic flux can be increased without increasing the size of the rotor, a small and high output motor can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the rotor which can suppress generation | occurrence | production of magnetic saturation and a motor provided with this can be provided.

(A) Sectional drawing of the motor of one Embodiment, (b) The perspective view of a rotating shaft similarly. The expanded sectional view of the rotor of one embodiment. The graph which shows the relationship between the thickness along the radial direction of a magnetic path augment, and the increase rate of the maximum value of the induced voltage which generate | occur | produces with a motor. (A) Sectional drawing of the rotor of another example, (b) The perspective view of a rotating shaft similarly. (A) Sectional drawing of the rotor of another example, (b) The perspective view of a rotating shaft similarly. (A) Sectional drawing of the rotor of another example, (b) The perspective view of a rotating shaft similarly. (A) Sectional drawing of the rotor of another example, (b) The perspective view of a rotating shaft similarly. (A) Sectional drawing of the rotor of another example, (b) The perspective view of a rotating shaft similarly.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1A, the motor 1 is configured with a rotor 3 disposed on the inner peripheral side of a substantially annular stator 2. The stator 2 includes a stator core 11 in which a plurality of teeth 12a (12 in the present embodiment) extending inward in the radial direction are provided in the circumferential direction, and a coil 12 wound around each tooth 11a.

  The rotor 3 includes a cylindrical rotary shaft 21 made of a nonmagnetic material (for example, stainless steel) and a substantially annular rotor core 22 fixed to the outer periphery of the rotary shaft 21. A through hole 26 having an inner diameter that is constant over the entire axial direction is formed at the center of the rotor core 22, while a plurality of (in this embodiment) are provided in the outer circumferential portion of the rotor core 22 in the circumferential direction of the rotor core 22. In this case, a plurality of magnet magnetic pole portions 24 are formed by embedding four magnets 23. Between the magnets 23, a core magnetic pole portion 25 formed integrally with the outer peripheral portion of the rotor core 22 is disposed with a gap K therebetween. That is, the rotor 3 according to the present embodiment employs a so-called continuous pole type structure having eight magnetic poles that causes the core magnetic pole portion 25 to function as the S pole with respect to the N magnetic pole portion 24. The magnet magnetic pole portions 24 and the core magnetic pole portions 25 are alternately arranged at equiangular intervals (45 ° intervals).

  Specifically, each magnet 23 is formed in a substantially rectangular parallelepiped shape that is long in the axial direction of the rotor core 22, and a cross section orthogonal to the axial direction of the rotor core 22 is formed in a rectangular shape. Each magnet 23 is arranged so that the longitudinal direction thereof is at the center and perpendicular to the radial direction, and the radially outer side is an N pole and the radially inner side is an S pole.

  As shown in FIG. 2, a plurality of magnet holes 31 penetrating in the axial direction are formed in the outer circumferential portion of the rotor core 22 at equal intervals in the circumferential direction of the rotor core 22. The magnet hole 31 includes a holding portion 31a formed in a rectangular shape substantially the same as the magnet 23 when viewed in the axial direction, and a pair of gap portions 31b formed on both sides in the circumferential direction of the holding portion 31a. The gap portion 31b is formed such that the length along the short direction (vertical direction in FIG. 2) of the holding portion 31a is shorter than the short direction length of the magnet 23 as viewed in the axial direction, and the rotor core 22 in the holding portion 31a. It is arrange | positioned at the radial direction outer side edge part. As a result, the radially inner side surface 32 on the inner circumferential surface of the magnet hole 31 has a stepped shape in which the central portion in the circumferential direction is recessed radially inward, and the magnet 23 is fitted into the recessed portion 32a. ing. The magnet hole 31 is formed in a line-symmetric shape with respect to a radial line passing through the center of the magnet 23 in the longitudinal direction, and is formed so as to have the same shape over the entire axial direction of the rotor core 22. Has been.

  Further, the outer surface 24a of the magnet magnetic pole portion 24 (the radially outer side surface of the portion disposed on the radially outer side of the holding portion 31a) gradually has a depth along the radial direction toward the both sides in the circumferential direction. A deep arc-shaped groove 34 that extends deeply extends along the axial direction of the rotor core 22. And the magnet magnetic pole part 24 and the core magnetic pole part 25 are connected by the bridge | bridging part 35 arrange | positioned at the radial direction outer side of the space | gap part 31b (gap K). In addition, the thickness along the radial direction of the bridge portion 35 is sufficiently thin, and the magnetic resistance of the magnet 23 is suppressed from passing through the bridge portion 35 by increasing its magnetic resistance.

  Here, as shown in FIGS. 1A and 1B, the rotary shaft 21 is provided with a small-diameter portion 21 a having a smaller diameter than other portions at a portion where the rotor core 22 is fixed, and the small-diameter portion 21 a. A plurality (four in this embodiment) of magnetic path augmenting bodies 41 as magnetic path augmenting means made of a magnetic material are fixed to the outer periphery.

  Specifically, the rotating shaft 21 has a small diameter portion 21a and a large diameter portion 21b having a larger diameter than the small diameter portions 21a provided at both ends of the small diameter portion 21a. The axial length of the small diameter portion 21 a is formed substantially equal to the axial length of the through hole 26 of the rotor core 22. A plurality of (four in this embodiment) reinforcing ribs 42 extending in the axial direction are integrally formed on the small diameter portion 21a. The reinforcing ribs 42 are arranged at equiangular intervals (90 ° intervals) in the circumferential direction of the rotating shaft 21, and are arranged to face the circumferential central portion 23 a of the magnet 23. In the present embodiment, each reinforcing rib 42 is formed in a straight line shape along the axial direction of the rotating shaft 21, and the thickness along the radial direction is the radius of the small diameter portion 21a and the radius of the large diameter portion 21b. It is formed in a substantially quadrangular cross section that is substantially equal to the difference between the two.

  Each magnetic path augment 41 is formed in a substantially arc plate shape, and is fixed between the reinforcing ribs 42 on the outer peripheral surface of the small diameter portion 21a. The thickness along the radial direction of the magnetic path augment 41 is formed to be approximately equal to the thickness along the radial direction of the reinforcing rib 42, and the length along the axial direction of the magnetic path augment 41 is approximately equal to the rotor core 22. Is formed. Further, the length along the circumferential direction of the magnetic path augment 41 is formed to be substantially equal to the circumferential interval between the adjacent reinforcing ribs 42. The rotor core 22 is fixed to the outer periphery of the small-diameter portion 21 a of the rotating shaft 21 by being press-fitted into the outer periphery of the magnetic path augment 41 and the reinforcing rib 42.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) Since the small-diameter portion 21a is provided at the portion of the rotating shaft 21 to which the rotor core 22 is fixed, and the magnetic path augment 41 made of a magnetic material is provided on the outer periphery of the small-diameter portion 21a, the magnetic path on the inner peripheral side of the magnet 23 A sufficient area can be secured. Therefore, generation of magnetic saturation can be suppressed without increasing the size of the rotor 3, and the effective magnetic flux can be increased. As a result, the maximum value of the induced voltage, which is a value proportional to the amount of magnetic flux interlinked with the coil 12, has a thickness along the radial direction of the magnetic path augmenter 41 (the radius of the small diameter portion 21a and the radius of the large diameter portion 21b). 3), the increase rate shown in FIG. 3 increases. Thereby, the small and high output motor 1 can be provided.

  (2) The magnet 23 has a rectangular cross section perpendicular to the axial direction of the rotary shaft 21. According to the above configuration, since the magnet 23 has a simple shape, for example, cost can be reduced. In addition, if the cross section of the magnet 23 is rectangular, the magnetic path on the inner peripheral side of the magnet 23 is likely to be narrow (the magnetic path area is small), and thus the effect of providing the magnetic path augment 41 on the small diameter portion 21a is large. is there.

(3) Since the reinforcing rib 42 extending in the axial direction of the rotary shaft 21 is formed on the small diameter portion 21a, strength reduction due to the provision of the small diameter portion 21a on the rotary shaft 21 can be suppressed.
(4) The reinforcing rib 42 is provided so as to face the circumferential central portion 23 a of the magnet 23 in the radial direction of the rotating shaft 21. Here, the magnetic flux of the magnet 23 returns to the magnet 23 mainly through the core magnetic pole portion 25 provided adjacent to both sides in the circumferential direction of the rotor core 22. For this reason, the magnetic flux density on the inner peripheral side of the magnet 23 in the rotor 3 is increased at both sides in the circumferential direction of the magnet 23 (approximately in the range A surrounded by the broken line in FIG. 2). It's hard to get high. Accordingly, by providing the reinforcing rib 42 so as to face the circumferential central portion 23a of the magnet 23 in the radial direction of the rotating shaft 21 as in the above configuration, the rotating shaft 21 is suitably suppressed while suppressing the occurrence of magnetic saturation. The strength of the can be ensured.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the above embodiment, the same number of reinforcing ribs 42 as the magnets 23 are formed in the small diameter portion 21a. However, the number of reinforcing ribs 42 may be any number, and for example, as many reinforcing ribs 42 as the number of magnets 23 may be formed as shown in FIGS. In the example shown in FIGS. 4A and 4B, the reinforcing rib 42 is located at a position facing the circumferential central portion 23 a of each magnet 23 and a position facing the circumferential central portion of the core magnetic pole portion 25. Is formed. With this configuration, it is possible to achieve the same effects as the above embodiment.

  Further, the reinforcing rib 42 may not be formed on the small diameter portion 21a, and the magnetic path augmenting member 41 may be formed in a substantially cylindrical shape as shown in FIGS. 5 (a) and 5 (b), for example. Even if comprised in this way, there can exist an effect similar to (1) and (2) of the said embodiment.

  In the above-described embodiment, the reinforcing rib 42 is provided so as to face the circumferential central portion 23a of the magnet 23. However, the present invention is not limited thereto, and the reinforcing rib 42 is opposed to other than the circumferential central portion 23a of the magnet 23. It may be provided.

  In the above embodiment, the cross-sectional shape of the reinforcing rib 42 is a quadrangular shape, and the circumferential width along the circumferential direction of the reinforcing rib 42 is formed to be substantially constant regardless of the radial position of the rotating shaft 21. . However, the present invention is not limited to this, and for example, as shown in FIGS. Good. In the example shown in FIGS. 6A and 6B, the magnetic path augment 41 is formed in a substantially semi-cylindrical shape.

  In the above-described embodiment, the magnetic path augmenting body 41 configured separately from the rotor core 22 is provided on the outer periphery of the small diameter portion 21a. However, the present invention is not limited to this, for example, as shown in FIGS. 7A and 7B, as magnetic path augmenting means that protrudes radially inward from the inner peripheral surface of the through hole 26 of the rotor core 22 and contacts the small diameter portion 21a. The arc-shaped extending portion 22a is integrally formed, and the rotary shaft 21 is provided with the large-diameter portion 21b only on one end side of the small-diameter portion 21a, and the rotor core 22 is press-fitted from the other axial end side of the rotary shaft 21. You may make it do.

  Further, in the configuration in which the rotary shaft 21 is provided with the large-diameter portion 21b only on one end side of the small-diameter portion 21a, for example, as shown in FIGS. You may form so that it may become small gradually toward the radial direction outer side. In the example shown in FIGS. 8A and 8B, the extending portion 22a integrally formed on the inner peripheral surface of the through hole 26 of the rotor core 22 is formed in a substantially semi-cylindrical shape. In the configuration shown in FIGS. 7 and 8, in addition to the same effects as the above-described embodiment, it is not necessary to provide a separate magnetic path augment, so that an increase in the number of parts can be suppressed.

  In the configuration in which the rotary shaft 21 is provided with the large-diameter portion 21b only on one end side of the small-diameter portion 21a, the circumferential width of the reinforcing rib 42 is formed so as to gradually increase toward the radially outer side of the rotary shaft 21. May be.

  In the above embodiment, the thickness of the reinforcing rib 42 along the radial direction is formed so as to be substantially equal to the difference between the radius of the small diameter portion 21a and the radius of the large diameter portion 21b. It can be large or small. In addition, the reinforcing rib 42 is not limited to a linear shape extending in the axial direction of the rotating shaft 21, and may have a curved shape, for example.

In the above embodiment, the cross section perpendicular to the axial direction of the rotating shaft 21 of the magnet 23 is formed in a rectangular shape, but the present invention is not limited thereto, and may be formed in an arc shape, for example.
In the above embodiment, the magnet 23 is arranged so that the radially outer side is the N pole and the radially inner side is the S pole. However, the magnet 23 is not limited to this, and the magnet 23 has the S pole on the radially outer side and the radially inner side. You may arrange | position so that it may become N pole.

-In the said embodiment, as long as the core magnetic pole part 25 is comprised so that it may function as the other magnetic pole, you may change the shape of the magnet magnetic pole part 24 and the core magnetic pole part 25 suitably.
In the above embodiment, the number of teeth 11a (and coils 12) is 12, and the number of magnets 23 (core magnetic pole portion 25) is 4, that is, the rotor 3 is 8 magnetic poles. Those numbers may be changed to other numbers.

  DESCRIPTION OF SYMBOLS 1 ... Motor, 3 ... Rotor, 21 ... Rotating shaft, 21a ... Small diameter part, 21b ... Large diameter part, 22 ... Rotor core, 22a ... Extension part as magnetic path augmentation means, 23 ... Magnet, 23a ... Circumferential center part , 24 ... magnet magnetic pole part, 25 ... core magnetic pole part, 31 ... magnet hole, 35 ... bridge part, 41 ... magnetic path augment as magnetic path augmenting means, 42 ... reinforcing rib, K ... gap.

Claims (5)

A magnet core part is formed by embedding a plurality of magnets of one magnetic pole in the circumferential direction in a rotor core fixed to a rotating shaft made of a non-magnetic material, and the core magnetic pole part formed on the rotor core is disposed between the magnets. A rotor arranged and configured such that the core magnetic pole portion functions as the other magnetic pole,
The rotating shaft is provided with a small diameter portion at a portion where the rotor core is fixed,
A rotor characterized in that magnetic path augmentation means made of a magnetic material is provided on the outer periphery of the small diameter portion. The rotor according to claim 1, wherein
The magnet is characterized in that a cross section perpendicular to the axial direction of the rotating shaft is formed in a rectangular shape. The rotor according to claim 1 or 2,
A rotor characterized in that a reinforcing rib extending in the axial direction of the rotating shaft is formed in the small diameter portion. The rotor according to claim 3, wherein
The rotor, wherein the reinforcing rib is provided so as to face a central portion in the circumferential direction of the magnet in a radial direction of the rotating shaft.   The motor provided with the rotor as described in any one of Claims 1-4.

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