JP2015146713A - Rotor, and motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor capable of being easily manufactured while achieving both reduction in a torque ripple and improvement of a detent torque.SOLUTION: A rotor 14 is an SPM type at an outer periphery of which a field magnet 22 is disposed. The field magnet 22 is constituted of a bond magnet. At an outer periphery surface of the field magnet 22, first and second auxiliary grooves 23a, 23b are provided as gap parts for improving a detent torque.

Description

  The present invention relates to a rotor and a motor.

  2. Description of the Related Art Conventionally, for example, an inner rotor type brushless motor includes a rotor having a field magnet on the outer peripheral surface of a rotor core, and a stator disposed to face the field magnet of the rotor (see, for example, Patent Document 1).

  A so-called IPM type rotor in which a field magnet is embedded in a rotor core is known in contrast to a type (so-called SPM type) rotor in which a field magnet appears on the outer peripheral surface, such as the rotor of Patent Document 1. In the IPM type rotor, the teeth interlinkage magnetic flux is easily distorted, whereas in the SPM type rotor, the teeth interlinkage magnetic flux approaches a sine wave. Therefore, the SPM type rotor is more advantageous in terms of suppressing torque ripple.

  By the way, when a brushless motor is used in an apparatus that requires a position holding function, a large detent torque (cogging torque) is required. Therefore, it is possible to improve the detent torque by providing a gap portion (a groove on the outer peripheral surface in Patent Document 1) in the field magnet or on the outer peripheral surface so that the change in the magnetic flux in the circumferential direction on the outer periphery of the rotor is increased. It becomes. That is, by arranging the field magnet on the outer peripheral surface of the rotor and forming a gap in the field magnet, both reduction of torque ripple and improvement of detent torque can be achieved.

JP 2007-215382 A

  However, although the rotor as described above can achieve both a reduction in torque ripple and an increase in detent torque, it is difficult to manufacture because a fine process such as a groove is added to the field magnet, and there is still room for improvement in this respect. there were.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotor and a motor that can be easily manufactured while simultaneously reducing torque ripple and improving detent torque. There is to do.

  A rotor that solves the above problems is a rotor that is configured such that a field magnet appears on at least a part of the outer periphery, and the field magnet is composed of a bonded magnet, and a gap is formed in the field magnet. I have.

  According to this configuration, a gap for improving the detent torque can be easily formed by employing a bonded magnet having a higher degree of freedom in shape than a sintered magnet. Therefore, it is possible to easily manufacture while achieving both reduction of torque ripple and improvement of detent torque.

In the rotor, it is preferable that the gap is a groove formed along the axial direction on the outer peripheral surface of the field magnet.
According to this structure, the space | gap part for improving a detent torque can be comprised easily.

The rotor is preferably a full magnet type in which all the magnetic poles of the rotor are constituted by the field magnets.
According to this configuration, the SPM type full magnet rotor can be easily manufactured while achieving both a reduction in torque ripple and an improvement in detent torque.

  In the rotor, a plurality of the field magnets of one magnetic pole are arranged in the circumferential direction of the rotor core, a core magnetic pole part formed on the rotor core is arranged between the field magnets, and the core magnetic pole part is placed on the other side It is preferable to be configured to function as a magnetic pole.

  According to this configuration, it is possible to easily manufacture an SPM type half magnet rotor (a consequent pole type rotor) while simultaneously reducing torque ripple and improving detent torque.

  In the rotor, a pair of core members each having a plurality of claw portions in the circumferential direction and combined, a disc magnet disposed between the axial directions of the pair of core members and magnetized in the axial direction, It is preferable to provide the field magnet provided on the outer periphery of the core member.

According to this configuration, it is possible to improve the output by providing the disc magnet separately from the field magnet.
A motor that solves the above problem is a motor that includes the rotor.

  According to this configuration, it is possible to easily manufacture while simultaneously reducing torque ripple and improving detent torque.

  According to the rotor and motor of the present invention, it is possible to easily manufacture while achieving both reduction of torque ripple and improvement of detent torque.

It is sectional drawing of the brushless motor of embodiment. It is a top view which shows the rotor of the same form partially. It is a graph for demonstrating the detent torque in the same form. It is a top view of the rotor of another example. It is a perspective view of the rotor of another example. It is a top view of the rotor of the another example. FIG. 7 is a cross-sectional view taken along line AA in FIG. 6. It is a disassembled perspective view of the rotor of the another example. It is a perspective view of the rotor of another example. It is a disassembled perspective view of the rotor of the another example.

Hereinafter, an embodiment of the brushless motor will be described.
As shown in FIG. 1, a brushless motor 10 has a stator 12 fixed to an inner peripheral surface of a motor housing 11, and a rotor 14 that is fixed to a rotating shaft 13 and rotates together with the rotating shaft 13 inside the stator 12. Is arranged.

  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. On the inner side of the stator core 15, a plurality (12 in this embodiment) of teeth 16 that are formed along the axial direction and arranged at an equal pitch in the circumferential direction are formed to extend inward in the radial direction. ing. Each tooth 16 is a T-shaped tooth, and its radially inner peripheral surface 16a is an arc surface obtained by extending a concentric arc centering on the axis L of the rotating shaft 13 in the axial direction.

  A three-phase winding 17 is wound around each tooth 16 by concentrated winding. 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 disposed inside the stator 12 is rotated. Yes.

[Configuration of rotor]
The rotor 14 disposed inside the stator 12 includes a substantially cylindrical rotor core 21 fixed to the rotary shaft 13 so as to be integrally rotatable, and a cylindrical field magnet 22 provided on the outer peripheral surface of the rotor core 21. Prepare. That is, the outer periphery of the rotor 14 is configured by the field magnet 22 over the entire circumferential direction. The rotor core 21 is configured by laminating a plurality of electromagnetic steel plates in the axial direction.

  The field magnet 22 is formed of a bonded magnet that is molded and solidified by mixing magnet powder with resin, and is integrally formed on the outer peripheral surface of the rotor core 21 by, for example, injection molding. The field magnet 22 may be fixed to the outer peripheral surface of the rotor core 21 with an adhesive or the like. Bonded magnets have a higher degree of freedom in shape than sintered magnets, and can be formed with high dimensional accuracy.

  The field magnet 22 is an eight-pole magnet having four north and south poles alternately in the circumferential direction, and each of the magnetic poles has an equal angular width (that is, 45 degrees). The rotor 14 is a full magnet type rotor in which all the magnetic poles are constituted by field magnets 22. In addition, the orientation direction of each magnetic pole of the field magnet 22 is along the radial direction centering on the rotating shaft 13.

  The outer peripheral surface of the field magnet 22 has a substantially circular shape with the axis L of the rotating shaft 13 as the center. The field magnet 22 has two grooves, a first auxiliary groove 23a and a second auxiliary groove 23b, on the outer peripheral surface of each magnetic pole. The first and second auxiliary grooves 23a and 23b are formed linearly from one end to the other end of the field magnet 22 in the axial direction, and the cross-sectional shape in the direction perpendicular to the axis is substantially U-shaped. .

Next, the formation positions of the first and second auxiliary grooves 23a and 23b will be described.
As shown in FIG. 2, with reference to the circumferential center line L1 of each magnetic pole of the field magnet 22, straight lines that are shifted from each other in the clockwise direction and the counterclockwise direction by an angle θ are respectively the first straight line L1a and the first straight line L1a. Let it be two straight lines L1b.

Here, the angle θ was obtained using the following arithmetic expression based on the period of cogging torque (angle φ).
θ = (1/2 + n) · φ
Note that n is an integer, and n = 0 in this embodiment.

  The period φ of the cogging torque is generally a value obtained by dividing 360 degrees by the least common multiple of the number of magnetic poles of the rotor 14 (field magnet 22) and the number of teeth 16 of the stator 12 (number of slots). That is, in this embodiment, the number of magnetic poles of the rotor 14 is 8 and the number of teeth 16 is 12, so the least common multiple is 24. The period φ of the cogging torque is 15 (= 360/24) degrees. Accordingly, the angle θ is 7.5 (= 15/2) degrees.

  On the outer peripheral surface of each magnetic pole of the field magnet 22, the first straight line L1a and the second straight line L1b that are displaced by 7.5 degrees in the clockwise direction and the counterclockwise direction about the circumferential center line L1 are surrounded. A groove having a certain width as a center position in the direction is recessed in the axial direction.

  A groove having the first straight line L1a in the circumferential center position is referred to as a first auxiliary groove 23a, and a groove having the second straight line L1b in the circumferential center position is referred to as a second auxiliary groove 23b. Therefore, the angle formed by each circumferential center of the first auxiliary groove 23a and the second auxiliary groove 23b with the axis L of the rotation shaft 13 as the center coincides with the period φ (= 15 degrees) of the cogging torque.

  That is, the angles of the first and second straight lines L1a and L1b from the circumferential center line L1 are both a half period (= 7.5 degrees) of the period φ of the cogging torque, and the first auxiliary groove 23a and the second auxiliary groove 23b is formed in a symmetrical position with the circumferential center line L1 as the axis of symmetry.

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. 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 angular position at which the stator 12 is magnetically most stable.

  Here, since the first and second auxiliary grooves 23a and 23b are formed on the outer peripheral surface of the field magnet 22 of the rotor 14, the change in the circumferential magnetic flux on the outer periphery of the rotor 14 is caused by the first and second. It is larger than before the auxiliary grooves 23a and 23b are formed. As a result, the holding force (detent torque) for returning the magnetic flux to a stable state is increased.

  In the present embodiment, the first auxiliary groove 23a and the second auxiliary groove 23b are formed in line-symmetrical positions with the circumferential center line L1 as an axis, and each circumference of the first auxiliary groove 23a and the second auxiliary groove 23b. The angle formed by the direction center coincides with the cogging torque period φ (= 15 degrees).

  For this reason, as shown in FIG. 3, the detent torque Ta before forming the first and second auxiliary grooves 23a, 23b (the detent torque when there is no first and second auxiliary grooves 23a, 23b) and The auxiliary groove detent torque Tb is in phase. Thus, the auxiliary groove detent torque Tb is superimposed on the pre-groove detent torque Ta so that the total detent torque Tc can be drawn to the maximum.

Next, characteristic effects of the present embodiment will be described.
(1) The rotor 14 is of the SPM type in which the field magnet 22 is disposed on the outer periphery, so that torque ripple can be reduced. By forming the auxiliary grooves 23a and 23b, the detent torque can be improved. Then, by employing a bond magnet having a higher degree of freedom in shape as compared with the sintered magnet for the field magnet 22, the gaps (first and second auxiliary grooves 23a and 23b) can be easily formed. As described above, according to the brushless motor 10 of the present embodiment, it is possible to easily manufacture while achieving both reduction of torque ripple and improvement of detent torque.

  (2) Since the gap for improving the detent torque is the first and second auxiliary grooves 23a and 23b formed along the axial direction on the outer peripheral surface of the field magnet 22, the gap can be easily configured. it can.

  (3) Since the angles of the first and second straight lines L1a and L1b from the circumferential center line L1 of the magnetic poles of the field magnet 22 are both a half period of the period φ of the cogging torque, the largest total detent torque Tc is obtained. Can be generated.

In addition, you may change the said embodiment as follows.
In the above embodiment, the magnetic poles of the rotor 14 are configured by the cylindrical field magnets 22. However, for example, the field magnets 22 may be divided for each magnetic pole.

  In the above embodiment, the rotor 14 is a full magnet type, but is not particularly limited to this, and may be a half magnet type (a continuous pole type) as shown in FIG. 4, for example.

  As shown in the figure, four core magnetic pole portions 31 (pseudo magnetic poles) projecting radially outward are integrally formed on the outer peripheral portion of the rotor core 21 at equal intervals in the circumferential direction (90-degree intervals). Each core magnetic pole part 31 is formed over the entire axial direction of the rotor core 21.

  Between the magnetic pole portions 31 on the outer peripheral surface of the rotor core 21, four field magnets 32 made of bonded magnets are fixed at equal intervals in the circumferential direction (90 ° intervals). Thereby, each field magnet 32 and the core magnetic pole part 31 are alternately arrange | positioned by the circumferential direction equal space | interval (45 degree space | interval).

  Each field magnet 32 has a magnetization orientation along the radial direction and is set to the same magnetic pole (N pole in FIG. 4). And the field magnet 32 makes the core magnetic pole part 31 function as a magnetic pole (S pole in FIG. 4) opposite to itself.

  The outer peripheral surfaces of the core magnetic pole portion 31 and the field magnet 32 are located on the same circle centered on the axis L of the rotary shaft 13 when viewed in the axial direction, and the outer peripheral surfaces constitute the outer peripheral surface of the rotor 14. doing. The first and second auxiliary grooves 23a and 23b similar to those of the above embodiment are formed on the outer peripheral surfaces of the core magnetic pole portion 31 and the field magnet 32.

  Even with such a configuration, it is possible to obtain the same effect as the above-described embodiment. That is, it is possible to easily manufacture an SPM type half-magnet rotor (continuous pole type rotor) while simultaneously reducing torque ripple and improving detent torque.

  In the above example, the first and second auxiliary grooves 23 a and 23 b are formed not only on the outer peripheral surface of the field magnet 32 but also on the outer peripheral surface of the core magnetic pole portion 31. The second auxiliary grooves 23a and 23b may be omitted.

-In the said embodiment, you may change the structure of the rotor core 21 and the field magnet 22 of the rotor 14 as shown in FIGS.
In the rotor shown in FIGS. 5 to 8, the rotor core 40 includes a first core member 41 and a second core member 51 having the same shape.

  As shown in FIGS. 7 and 8, the first core member 41 has a substantially disk-shaped first core base 42 having a fixing hole 42a through which the rotary shaft 13 is inserted and fixed. A plurality of (four in the present embodiment) first claw portions 43 are formed on the outer peripheral portion of the first core base 42 so as to protrude radially outward and extend in the axial direction at equal intervals.

  The second core member 51 has the same shape as the first core member 41, and corresponds to the first core base 42 (fixing hole 42 a) and the first claw portion 43 of the first core member 41, respectively. (Fixing hole 52a) and second claw portion 53 are provided. The second core member 51 is assembled to the first core member 41 so that each second claw portion 53 is disposed between each corresponding first claw portion 43.

  A disc magnet 61 is arranged between the first core base 42 and the second core base 52 in the axial direction. The disc magnet 61 has an annular shape, and the rotation shaft 13 passes through the center portion thereof. Further, the end face in the axial direction of the disc magnet 61 has a planar shape perpendicular to the axis L of the rotating shaft 13 and is in close contact with the inner end faces of the first and second core bases 42 and 52.

  The first claw portion 43 is radially spaced from the outer peripheral surface of the second core base 52 and the outer peripheral surface of the disc magnet 61. Further, the front end surface in the axial direction of the first claw portion 43 is flush with the outer end surface of the second core base 52.

  Similarly, the second claw portion 53 is radially spaced from the outer peripheral surface of the first core base 42 and the outer peripheral surface of the disc magnet 61. Further, the tip end surface in the axial direction of the second claw portion 53 is flush with the outer end surface of the first core base 42.

  The disc magnet 61 causes the first claw portion 43 to function as a first magnetic pole (N pole in this embodiment), and causes the second claw portion 53 to function as a second magnetic pole (S pole in this embodiment). In addition, it is magnetized in the axial direction.

  As shown in FIGS. 5 and 6, a field magnet 62 having a substantially cylindrical shape is provided on the outer periphery of the first and second core members 41 and 51. The field magnet 62 is composed of a bond magnet, similar to the field magnet 22 of the above-described embodiment, and the magnetic pole configuration and outer peripheral surface shape (first and second auxiliary grooves 23a, 23b) are the same as those of the above-described embodiment. It is the same.

  On the inner peripheral surface of the field magnet 62, eight projecting portions 63 are formed to project radially inward. The protruding portion 63 enters between the first claw portion 43 and the second claw portion 53 in the circumferential direction, and is in contact with the first claw portion 43 and the second claw portion 53 in the circumferential direction. Thereby, the idling of the field magnet 62 is prevented.

  According to the rotor having the above-described configuration, in addition to the same effects as those of the above-described embodiment, the output can be improved by adding the disc magnet 61. In addition, the said structure can also be considered as the structure which provided the field magnet 62 in the outer periphery of the rotor of what is called a Landel type structure using the 1st core member 41, the 2nd core member 51, and the disc magnet 61. FIG.

  In the above example, the field magnet 62 (projecting portion 63) may be integrally formed with a portion that fills the space on the inner peripheral side of the first and second claw portions 43 and 53. Moreover, the protrusion part 63 in said example is omissible.

Further, the present invention can also be applied to the type of rotor shown in FIGS.
The rotor shown in the figure is configured by assembling a flat rotor core 71 and an annular field magnet 72 made of a bond magnet in the axial direction.

  The rotor core 71 includes a thin disk-shaped core base 73 having a fixing hole 73a through which the rotating shaft 13 is inserted and fixed, and four claw-shaped magnetic poles 74 formed on the outer periphery of the core base 73 at equal intervals in the circumferential direction. . The claw-shaped magnetic pole 74 protrudes radially outward from the core base 73 and extends in the axial direction along the outer peripheral surface of the field magnet 72 (annular portion 75).

  The field magnet 72 has an annular portion 75 that forms an annular shape, and four salient pole portions 76 that protrude radially outward from the annular portion 75. The annular portion 75 is in axial contact with a portion extending in the radial direction from the core base 73 in the claw-shaped magnetic pole 74.

  The salient pole portions 76 are positioned between the claw-shaped magnetic poles 74 in the circumferential direction, and the salient pole portions 76 and the claw-shaped magnetic poles 74 are alternately arranged at equal intervals in the circumferential direction (45-degree intervals). A gap is set between the salient pole portion 76 and the claw-shaped magnetic pole 74 in the circumferential direction. Further, the annular portion 75 is in contact with the claw-shaped magnetic pole 74 in the radial direction between the salient pole portions 76.

  The field magnet 72 is an eight-pole magnet having four north and south poles alternately in the circumferential direction, and each of the magnetic poles has an equal angular width (that is, 45 degrees). And the salient pole part 76 is N pole, and the site | part which contact | abuts the claw-shaped magnetic pole 74 in the annular part 75 to radial direction becomes a S pole. In addition, the orientation direction of each magnetic pole of the field magnet 72 is along the radial direction centering on the rotating shaft 13.

  The outer peripheral surfaces of the salient pole portion 76 and the claw-shaped magnetic pole 74 are located on the same circle centered on the axis L of the rotary shaft 13 when viewed in the axial direction, and each outer peripheral surface forms the outer peripheral surface of the rotor. ing. That is, the salient pole portion 76 and the claw-shaped magnetic pole 74 constitute the magnetic pole of the rotor. The first and second auxiliary grooves 23a and 23b similar to those of the above embodiment are formed on the outer peripheral surfaces of the salient pole portion 76 and the claw-shaped magnetic pole 74.

  According to the rotor having the above configuration, the same effects as those of the above embodiment can be obtained. Furthermore, in this example, there is no rotor core inside the field magnet 72 (annular portion 75), and the inside of the field magnet 72 is a recess with the core base 73 as the bottom. For this reason, it becomes possible to arrange | position the bearing which supports the rotating shaft 13 in the space inside the field magnet 72, As a result, it becomes possible to achieve shaft shortening.

  In the above example, the first and second auxiliary grooves 23a and 23b are formed not only on the outer peripheral surface of the salient pole portion 76 (field magnet 72) but also on the outer peripheral surface of the claw-shaped magnetic pole 74. The first and second auxiliary grooves 23a and 23b of the magnetic pole 74 may be omitted.

  In the above embodiment, the first and second straight lines L1a and L1b that determine the intermediate positions in the circumferential direction of the first and second auxiliary grooves 23a and 23b are determined based on the period (angle φ) of the cogging torque. The first and second auxiliary grooves 23a and 23b may be formed at positions different from those in the above embodiment. In this case, although the detent torque is small, it can be used when adjusting the magnitude of the detent torque.

  In the above embodiment, the gap for improving the detent torque is the first and second auxiliary grooves 23a and 23b formed on the outer peripheral surface of the field magnet 22, but is not particularly limited thereto. . For example, even if the hole formed in the axial direction of the field magnet 22 is used as a gap (that is, the opening end of the first and second auxiliary grooves 23a, 23b on the radially outer side is closed), The substantially same effect as the above embodiment can be obtained.

In the above embodiment, the number of magnetic poles of the rotor 14 may be changed as appropriate according to the configuration.
In each of the above embodiments, the rotor 14 is embodied as an inner rotor type motor in which the rotor 14 is disposed on the inner peripheral side of the stator 12. However, the present invention is not particularly limited thereto, and the outer rotor type in which the rotor is disposed on the outer peripheral side of the stator. It may be embodied in the motor.

  DESCRIPTION OF SYMBOLS 10 ... Brushless motor, 12 ... Stator, 13 ... Rotating shaft, 14 ... Rotor, 21, 40, 71 ... Rotor core, 22, 32, 62, 72 ... Field magnet, 23a ... 1st auxiliary groove (groove part), 23b ... 2nd auxiliary groove (groove part), 31 ... core magnetic pole part, 41 ... 1st core member, 51 ... 2nd core member, 61 ... disc magnet.

Claims (6)

A rotor configured such that a field magnet appears on at least a part of the outer periphery,
A rotor characterized in that the field magnet is composed of a bonded magnet, and the field magnet is provided with a gap. The rotor according to claim 1, wherein
The rotor is characterized in that the gap is a groove formed along the axial direction on the outer peripheral surface of the field magnet. The rotor according to claim 1 or 2,
A rotor of a full magnet type in which all the magnetic poles of the rotor are composed of the field magnets. The rotor according to claim 1 or 2,
A plurality of the field magnets of one magnetic pole are arranged in the circumferential direction of the rotor core, and a core magnetic pole part formed in the rotor core is arranged between the field magnets, and the core magnetic pole part functions as the other magnetic pole. A rotor configured to do so. The rotor according to claim 1 or 2,
A pair of core members each having a plurality of claw portions in the circumferential direction and combined;
A disc magnet disposed between the pair of core members in the axial direction and magnetized in the axial direction;
A rotor comprising: the field magnet provided on an outer periphery of the core member.   A motor comprising the rotor according to claim 1.