JP6027902B2 - motor - Google Patents

Description

  The present invention relates to a motor.

  Patent Document 1 proposes a brushless motor employing a rotor with a magnet field Landell type structure. This Landel-type rotor is excellent in that the structure is simple and downsizing can be realized because the magnet is arranged between two rotor cores of the same material and the same shape.

Japanese Utility Model Publication No. 5-43749

  By the way, when a brushless motor is used in an apparatus that requires a position holding function, a large detent torque is required. However, in a brushless motor that employs a Landel-type rotor having a magnet field, the claw-shaped magnetic poles of the rotor core are opposed to the teeth of the stator core. Therefore, a brushless motor employing a magnet field Landell-type rotor has a disadvantage that the detent torque is small and the holding force for holding the stationary motor at that position is weak.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor with improved detent torque and strong holding force.

In the motor that solves the above-described problem, a plurality of first claw-shaped magnetic poles are arranged on the outer peripheral surface of the circular first core base that rotates integrally with the rotation shaft around the rotation shaft at equal intervals. The outer periphery of the first rotor core that is projected and bent to extend in the axial direction and that extends in the axial direction and the circular second core base that rotates integrally with the rotation shaft about the rotation shaft are equally spaced. A plurality of second claw-shaped magnetic poles project radially outward and have their tips bent to extend in the axial direction, and the second claw-shaped magnetic poles are adjacent to each other in the circumferential direction. A second rotor core disposed between the first rotor core and the second core base of the first rotor core and the second core core of the second rotor core. Each of the first claws is magnetized along the axial direction. A rotor including a field magnet that causes a magnetic pole to function as a first magnetic pole and each of the second claw-shaped magnetic poles to function as a second magnetic pole; and a radially inner circumferential surface disposed outside the rotor Includes a stator core provided with a plurality of teeth facing the radially outer circumferential surfaces of the first and second claw-shaped magnetic poles at equal intervals in the circumferential direction, and a winding that is wound around each of the teeth and generates a rotating magnetic field when energized. A motor comprising a stator with wires,
The cross-sectional shape of the teeth in the radial direction on the radially inner circumferential surface is not a concentric circle centered on the central axis of the rotating shaft.

  According to this configuration, since the cross-sectional shape in the direction perpendicular to the axis of the radially inner circumferential surface of the teeth does not become a concentric circle centered on the central axis of the rotating shaft, the change in magnetic flux accompanying the movement increases, and the magnetic flux is stabilized. The holding force (detent torque) to return to increases.

  In the above configuration, a tooth side auxiliary groove extending along the axial direction is formed on the radially inner peripheral surface of the teeth, and the axial orthogonal cross-sectional shape of the radially inner peripheral surface of the teeth is centered on the central axis of the rotating shaft It is preferable to avoid concentric circles.

  According to this configuration, the teeth-side auxiliary grooves are formed on the radially inner circumferential surface so that the cross-sectional shape in the direction perpendicular to the axis of the radially inner circumferential surface does not become a concentric circle centered on the central axis of the rotating shaft. Therefore, the change in the magnetic flux accompanying the movement increases, and the holding force (detent torque) for returning the magnetic flux to a stable state increases.

  In the above configuration, when the period of the cogging torque is φ and the number of magnetic poles of the rotor is Nr, the teeth side auxiliary groove is the central axis of the rotating shaft that intersects the circumferential center position of the radially inner circumferential surface of the teeth. When the angle formed with the center line from θ is θs, it is formed at a position in the range of − (360 / φ) / (Nr / 2) ≦ θs ≦ (360 / φ) / (Nr / 2) in the circumferential direction. It is preferable.

According to this configuration, the holding force (detent torque) for returning the magnetic flux to a stable state can be increased by the teeth side auxiliary groove formed on the radially inner peripheral surface.
In the above configuration, the teeth side auxiliary groove preferably has a U-shaped cross section in the direction perpendicular to the axis, and is formed along the axial direction at one central position in the circumferential direction of the radially inner peripheral surface of the teeth. .

According to this configuration, the same holding force (detent torque) can be generated in any rotation direction of the rotor.
In the above-described configuration, it is preferable that the first claw-shaped magnetic pole and the second claw-shaped magnetic pole have a cross-sectional shape in a direction perpendicular to the axis of the radially outer circumferential surface that is not concentric with the central axis of the rotating shaft as the center.

  According to this configuration, in addition, the axial orthogonal cross-sectional shape of the radially inner circumferential surface of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole does not become a concentric circle centered on the central axis of the rotating shaft. The accompanying change in magnetic flux increases, and the holding force (detent torque) for returning the magnetic flux to a stable state increases.

  In the above configuration, a rotor side auxiliary groove extending along the axial direction is formed on the radially outer circumferential surface of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole, and the first claw-shaped magnetic pole and the second claw-shaped magnetic pole are formed. It is preferable that the cross-sectional shape of the radially outer peripheral surface in the direction perpendicular to the axis does not become a concentric circle centered on the central axis of the rotating shaft.

  According to this configuration, the rotor-side auxiliary groove formed on the radially outer circumferential surface is formed so that the cross-sectional shape of the radially outer circumferential surface in the direction orthogonal to the axis does not become a concentric circle centered on the central axis of the rotating shaft. Therefore, the change in the magnetic flux accompanying the movement increases, and the holding force (detent torque) for returning the magnetic flux to a stable state increases.

  In the above-described configuration, the rotor side auxiliary groove extends along the axial direction from the circumferential center position of the radially outer circumferential surface of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole to a position half the period of the cogging torque on both circumferential sides. It is preferable that the first auxiliary groove and the second auxiliary groove are formed.

  According to this configuration, the angle formed by the first auxiliary groove and the second auxiliary groove is formed so as to coincide with the period (angle) of the cogging torque, so the torque by the first and second auxiliary grooves increases. The detent torque increases. Moreover, it has the same holding force (detent torque) in any rotation direction of the rotor.

  In the above configuration, the rotor is magnetized to be the same as the first claw-shaped magnetic pole and the second claw-shaped magnetic pole between the first claw-shaped magnetic pole and the second claw-shaped magnetic pole adjacent in the circumferential direction. It is preferable to arrange the inter-electrode auxiliary magnet.

According to this configuration, the magnetic flux is increased by the inter-pole auxiliary magnet, and the holding force (detent torque) is further increased.
According to the above configuration, the rotor is the same as the first claw-shaped magnetic pole and the second claw-shaped magnetic pole on the radially inner peripheral surface side of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole, respectively. It is preferable to arrange a back auxiliary magnet magnetized so as to be.

  According to this configuration, the back auxiliary magnet increases the magnetic flux, and the holding force (detent torque) can be further increased.

  According to the present invention, a motor with improved detent torque and strong holding force can be realized.

Sectional drawing seen from the axial direction of the brushless motor of 1st Embodiment. Similarly, the principal part enlarged front view seen from the axial direction for demonstrating the teeth structure of a stator. Similarly, (a) is a perspective view of the rotor viewed from the first rotor core side, and (b) is a perspective view of the rotor viewed from the second rotor core side. Similarly, the front view which looked at the rotor from the axial direction. Similarly, the AOB line combination sectional drawing of FIG. Similarly, the exploded perspective view of a rotor. Similarly, the figure which shows the relationship of each detent torque. Sectional drawing seen from the axial direction of the brushless motor of 2nd Embodiment. Similarly, the front view which looked at the rotor from the axial direction. Similarly, the figure which shows the relationship of each detent torque. Sectional drawing seen from the axial direction of the brushless motor for demonstrating another example. Similarly, (a) is a perspective view of the rotor viewed from the first rotor core side, and (b) is a perspective view of the rotor viewed from the second rotor core side.

(First embodiment)
Hereinafter, a first embodiment of the motor will be described.
As shown in FIG. 1, a brushless motor M has a stator 2 fixed to an inner peripheral surface of a motor housing 1, and a so-called Landel that is fixed to a rotating shaft 3 and rotates integrally with the rotating shaft 3 inside the stator 2. A rotor 4 having a mold structure is provided. The rotating shaft 3 is a stainless steel shaft made of a magnetic material, and is supported by a bearing (not shown) provided on the motor housing 1 so as to be rotatable with respect to the motor housing 1.

(Stator 2)
The stator 2 has a cylindrical stator core 10, and the outer peripheral surface of the stator core 10 is fixed to the inner peripheral surface of the motor housing 1. Inside the stator core 10, a plurality of teeth 11 formed along the axial direction and arranged at equal pitches in the circumferential direction are formed extending inward in the radial direction. Each tooth 11 is a T-shaped tooth, and an inner circumferential surface 11 a in the radial direction is an arc surface obtained by extending a concentric arc centering on the central axis O of the rotating shaft 3 in the axial direction.

  A slot 12 is formed between the teeth 11. In the present embodiment, the number of teeth 11 is twelve, and the number of slots 12 is twelve, which is the same as the number of teeth 11. Around the 12 teeth 11, a three-phase winding, that is, a U-phase winding 13u, a V-phase winding 13v, and a W-phase wire 13w are wound in order in a concentrated manner in the circumferential direction.

  Then, a three-phase power supply voltage is applied to each of the wound phase windings 13u, 13v, and 13w to form a rotating magnetic field in the stator 2, and the rotor 4 fixed to the rotating shaft 3 disposed inside the stator 2 is provided. Are rotated in the forward direction (clockwise direction in FIG. 1) and in the reverse direction (rotated in the counterclockwise direction in FIG. 1).

  As shown in FIG. 1, teeth-side auxiliary grooves 15 are provided on the inner peripheral surface 11 a of each tooth 11. More specifically, as shown in FIG. 2, a straight line that is the inner peripheral surface 11 a of each tooth 11 and passes through the intermediate position in the circumferential direction of each tooth 11 from the center axis O of the rotation shaft 3 is defined as a center line Lk. . A teeth side auxiliary groove 15 having a U-shaped cross section with the center line Lk as a center is recessed in the axial direction. The teeth-side auxiliary groove 15 is formed in a U-shaped cross section in the direction perpendicular to the axis, and its bottom surface 15a is flat and formed at right angles to the side surfaces extending from the radially inner side from both sides.

As a result, the inner peripheral surface 11 a including the bottom surface 15 a of the tooth side auxiliary groove 15 does not have a concentric circle whose center is perpendicular to the central axis O of the rotating shaft 3.
(Rotor 4)
As shown in FIGS. 3 to 5, the Landel-type rotor 4 disposed inside the stator 2 is a rotor having eight magnetic poles, and includes first and second rotor cores 20 and 30, field magnets. 40.

(First rotor core 20)
As shown in FIG. 6, the first rotor core 20 is formed of a magnetic steel plate made of a soft magnetic material, and has a disk-shaped first core base 21 in which a through hole 20 a that penetrates and fixes the rotating shaft 3 is formed. doing. On the outer peripheral surface 21c of the first core base 21, a plurality of (four in the present embodiment) first claw-shaped magnetic poles 22 project radially outward and extend in the axial direction at equal intervals. Here, in the first claw-shaped magnetic pole 22, a portion protruding radially outward from the outer peripheral surface 21 c of the first core base 21 is referred to as a first base portion 23, and a tip portion bent in the axial direction is the first magnetic pole portion 24. That's it.

  Both circumferential end surfaces 22a and 22b of the first claw-shaped magnetic pole 22 composed of the first base portion 23 and the first magnetic pole portion 24 are flat surfaces extending in the radial direction. The circumferential angle of each first claw-shaped magnetic pole 22, that is, the angle between the circumferential end surfaces 22 a and 22 b is set smaller than the angle of the gap between the first claw-shaped magnetic poles 22 adjacent in the circumferential direction. Yes.

  As shown in FIG. 4, the radially outer peripheral surface f <b> 1 of the first magnetic pole portion 24 is an arc surface obtained by extending a concentric arc centering on the central axis O of the rotating shaft 3 in the axial direction. The radially inner peripheral surface f1b of the first magnetic pole portion 24 is an arc surface obtained by extending a concentric arc centering on the central axis O of the rotation shaft 3 in the axial direction. Therefore, the cross-sectional shape of the first magnetic pole portion 24 in the direction perpendicular to the axis is a fan shape.

(Second rotor core 30)
As shown in FIG. 6, the second rotor core 30 is the same material and the same shape as the first rotor core 20, and has a disk-like second core base 31 in which a through hole 30 a that penetrates and fixes the rotating shaft 3 is formed. have. On the outer peripheral surface 31c of the second core base 31, four second claw-shaped magnetic poles 32 are formed at equal intervals so as to protrude radially outward and extend in the axial direction. Here, in the second claw-shaped magnetic pole 32, a portion that protrudes radially outward from the outer peripheral surface 31 c of the second core base 31 is referred to as a second base portion 33, and a tip portion bent in the axial direction is the second magnetic pole portion 34. That's it.

  The circumferential end surfaces 32a and 32b of the second claw-shaped magnetic pole 32 composed of the second base portion 33 and the second magnetic pole portion 34 are flat surfaces extending in the radial direction. The circumferential angle of each of the second claw-shaped magnetic poles 32, that is, the angle between the circumferential end surfaces 32a and 32b is set smaller than the angle of the gap between the second claw-shaped magnetic poles 32 adjacent in the circumferential direction. Yes.

  As shown in FIG. 4, the radially outer circumferential surface f <b> 2 of the second magnetic pole portion 34 is an arc surface obtained by extending a concentric arc centering on the central axis O of the rotation shaft 3 in the axial direction. The radial inner peripheral surface f2b of the second magnetic pole portion 34 is an arc surface obtained by extending a concentric arc centering on the central axis O of the rotating shaft 3 in the axial direction. Accordingly, the cross-sectional shape of the second magnetic pole portion 34 in the direction perpendicular to the axis is a fan shape.

  The second rotor core 30 is disposed between the first claw-shaped magnetic poles 22 to which the second claw-shaped magnetic poles 32 respectively correspond. At this time, the second rotor core 30 is configured such that the field magnet 40 (see FIG. 5) is disposed (sandwiched) between the first core base 21 and the second core base 31 in the axial direction. 20 is assembled.

(Field magnet 40)
As shown in FIGS. 5 and 6, the field magnet 40 sandwiched between the first rotor core 20 and the second rotor core 30 is a disk-like permanent magnet made of a neodymium magnet.

  As shown in FIG. 6, the field magnet 40 has a through hole 41 penetrating the rotating shaft 3 at the center position. Then, one side surface 40a of the field magnet 40 is in contact with the opposing surface 21a of the first core base 21 and the other side surface 40b of the field magnet 40 is in contact with the opposing surface 31a of the second core base 31, respectively. The magnet 40 is sandwiched and fixed between the first rotor core 20 and the second rotor core 30.

The outer diameter of the field magnet 40 is set to coincide with the outer diameters of the first and second core bases 21 and 31, and the thickness is set to a predetermined thickness.
That is, as shown in FIG. 5, when the field magnet 40 is disposed between the first rotor core 20 and the second rotor core 30, the tip surface 22c of the first claw-shaped magnetic pole 22 (first magnetic pole portion 24) The opposite surface 31b of the second core base 31 is flush with the surface. Similarly, the tip surface 32c of the second claw-shaped magnetic pole 32 (second magnetic pole portion 34) and the opposite surface 21b of the first core base 21 are flush with each other. Further, the outer peripheral surface 40 c of the field magnet 40 is flush with the outer peripheral surfaces 21 c and 31 c of the first and second core bases 21 and 31.

  As shown in FIG. 5, the field magnet 40 is magnetized in the axial direction, and the first rotor core 20 side is an N pole (first magnetic pole), and the second rotor core 30 side is an S pole (second magnetic pole). It is magnetized so that Therefore, by this field magnet 40, the first claw-shaped magnetic pole 22 of the first rotor core 20 functions as an N pole (first magnetic pole), and the second claw-shaped magnetic pole 32 of the second rotor core 30 functions as an S pole (second magnetic pole). Function as a magnetic pole).

  Therefore, the rotor 4 of the present embodiment is a so-called Landell type rotor using the field magnet 40. In the rotor 4, the first claw-shaped magnetic poles 22 that are N poles and the second claw-shaped magnetic poles 32 that are S poles are alternately arranged in the circumferential direction, and the number of magnetic poles is eight.

  Further, since the number of magnetic poles of the rotor 4 is 8 and the number of teeth 11 (slots 12) of the stator 2 is 12, the brushless motor M is a 2N pole / 3N slot system (N is a natural number) brushless motor. .

Next, the operation of the embodiment configured as described above will be described below.
Now, in the brushless motor M, when a three-phase power supply voltage is applied to each phase winding 13u, 13v, 13w of the stator core 10 to form a rotating magnetic field on the stator 2, it is fixed to the rotating shaft 3 arranged inside the stator 2. The rotor 4 thus rotated rotates based on the rotating magnetic field.

  When the application of the three-phase power supply voltage to each phase winding 13u, 13v, 13w is stopped, the rotating magnetic field disappears and the rotor 4 stops rotating. At this time, in the rotor 4, the magnetic flux that the first magnetic pole portion 24 of the first rotor core 20 flows into the teeth 11 of the stator core 10 and the magnetic flux that flows from the teeth 11 of the stator core 10 into the second magnetic pole portions 34 of the second rotor core 30 are the most. Stop at the pivot position where it becomes stable.

  This stop position is the same as the inner peripheral surface 11a of every other tooth 11 where the radially outer peripheral surface f1 (radial outer peripheral surface f2) of any one of the first and second magnetic pole portions 24, 34 is located outside. Confront. More specifically, the center line Lk intersecting the circumferential intermediate position of the teeth side auxiliary groove 15 of every other tooth 11 passes through the circumferential intermediate position of the first magnetic pole portion 24 from the central axis O of the rotating shaft 3. The center line L1 shown in FIG. 4 (or the radial outer peripheral surface f2 of the second magnetic pole portion 34, which passes through the intermediate position in the circumferential direction of the second magnetic pole portion 34 from the central axis O of the rotation shaft 3). ).

  In FIG. 1, the radially inner peripheral surface 11a of the teeth 11 facing the radially outer peripheral surface f1 of the first magnetic pole portion 24 is opposed to the center line L1 of the radially outer peripheral surface f1 of the first magnetic pole portion 24, respectively. The case where it is located in line with the center line Lk of the radial direction inner peripheral surface 11a of the teeth 11 facing each other is shown.

  At this time, since the brushless motor M is a motor with the rotor 4 having 8 poles and the stator 2 having 12 throttles, the center line L2 on the radial outer peripheral surface f2 of the second magnetic pole portion 34 is formed between the teeth 11 and 11. Located in the middle position.

  In this state, when the rotor 4 (rotating shaft 3) is rotated, the radially outer circumferential surface f1 of the first magnetic pole portion 24 moves in the circumferential direction with respect to the radially inner circumferential surface 11a of the teeth 11 facing each other. .

  At this time, since the tooth-side auxiliary groove 15 is formed on the inner peripheral surface 11 a of the tooth 11, the cross-sectional shape in the direction perpendicular to the axis does not become a concentric circle centered on the central axis O of the rotating shaft 3. Therefore, the change in the magnetic flux accompanying the movement is very large compared to the inner peripheral surface of the tooth without the teeth side auxiliary groove 15 that is a concentric circle centered on the central axis of the rotating shaft 3.

  Incidentally, the holding force (detent torque) for returning the magnetic flux to a stable state is relative to the change of the magnetic field. As a result, in this case, since the change of the magnetic field is very large, the holding force (detent torque) becomes large.

  FIG. 7 shows a comparison between the detent torque Ta without the teeth side auxiliary groove 15 and the detent torque T1 with the teeth side auxiliary groove 15 on the inner peripheral surface 11a of the teeth 11 obtained by the experiment.

7 that the detent torque T1 when the teeth side auxiliary groove 15 is formed is larger than the detent torque Ta when the teeth side auxiliary groove 15 is not provided.
And the teeth side auxiliary groove 15 is formed so that the center position of the bottom face 15a may be located on the center line Lk. Accordingly, the rotor 4 (rotating shaft 3) has the same holding force (detent torque) in any rotation direction.

Next, the effect of the said embodiment is described below.
(1) According to the present embodiment, since the tooth side auxiliary groove 15 is formed on the inner peripheral surface 11a of the tooth 11, the detent torque can be increased and the holding force of the brushless motor M in a stationary state can be increased. .

  (2) According to this embodiment, since the teeth side auxiliary groove 15 formed on the inner peripheral surface 11a of the tooth 11 is formed around the center line Lk of the inner peripheral surface 11a, the rotor 4 (rotating shaft 3) The same holding force (detent torque) can be generated in any rotation direction.

(Second Embodiment)
Next, a second embodiment of the motor will be described.
As shown in FIG. 8, the brushless motor M of the second embodiment includes the first and second claw-shaped magnetic poles 22 and 32 of the rotor 4, and the first and second claw-shaped magnetic poles 22 and 32 are arranged on the outer peripheral surface f <b> 1 of the first magnetic pole portion 24. The second auxiliary grooves 25 and 26 are formed, and the first and second auxiliary grooves 35 and 36 are formed on the outer peripheral surface f2 of the second magnetic pole portion 34. Therefore, the characteristic part is demonstrated in detail and description of another structure is abbreviate | omitted for convenience.

(First rotor core 20)
As shown in FIG. 9, the radial outer peripheral surface f1 of the first magnetic pole portion 24 of the first claw-shaped magnetic pole 22 has a concentric circular arc surface whose center is perpendicular to the central axis O of the rotation shaft 3. In addition, the outer circumferential surface f1 has two grooves, a first auxiliary groove 25 and a second auxiliary groove 26.

  More specifically, as shown in FIG. 9, a straight line that is the outer circumferential surface f <b> 1 in the radial direction of the first magnetic pole part 24 and passes through the intermediate position in the circumferential direction of the first magnetic pole part 24 from the central axis O of the rotating shaft 3. The center line is L1. Straight lines extending from the central axis O located at an angle θ1 in the clockwise direction and the counterclockwise direction with respect to the center line L1 are defined as a first straight line L1a and a second straight line L1b, respectively.

Here, the angle θ1 was obtained using the following arithmetic expression based on the period φ (angle) of the cogging torque (detent torque).
θ1 = (1/2 + n) · φ
Note that n is an integer, and in this embodiment, n = 0.

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 4 and the number of slots of the stator 2.
At this time, since the number of magnetic poles of the rotor 4 is 8 and the number of slots of the stator 2 is 12, the least common multiple is 24. The period φ of the cogging torque is 15 (= 360/24) degrees.

Accordingly, the angle θ1 is 7.5 (= 15/2) degrees.
Then, on the radially outer circumferential surface f1, the first straight line L1a and the second straight line L1b, which are respectively displaced by 7.5 degrees in the clockwise direction and the counterclockwise direction around the center line L1, are constant as the intermediate positions in the circumferential direction. Grooves having a width of 1 mm are recessed in the axial direction.

  And the groove | channel which makes the 1st straight line L1a the circumferential direction intermediate position is the 1st auxiliary groove 25, and the groove | channel which makes the 2nd straight line L1b the circumferential direction intermediate position is the 2nd auxiliary groove 26 on the contrary. Accordingly, the angle formed by the first auxiliary groove 25 and the second auxiliary groove 26 about the central axis O of the rotation shaft 3 coincides with the cogging torque period φ (= 15 degrees).

  That is, the angle formed by the center line L1 and the first straight line L1a and the angle formed by the center line L1 and the second straight line L1b are both a half period (= 7.5 degrees) of the period φ of the cogging torque. The second auxiliary groove 26 is formed at a symmetrical position with the center line L1 as the axis of symmetry.

  The first and second auxiliary grooves 25, 26 are formed in a U-shaped cross section in the direction perpendicular to the axis, the bottom surfaces 25 a, 26 a are flat, and are perpendicular to the side surfaces extending from the radially outer side from both sides. Is formed.

  Accordingly, the bottom surfaces 25 a and 26 a of the first and second auxiliary grooves 25 and 26 have a planar shape, so that the cross-sectional shape perpendicular to the axis does not become a concentric arc centered on the central axis O of the rotation shaft 3. As a result, the radial outer peripheral surface f1 including the bottom surfaces 25a and 26a of the first and second auxiliary grooves 25 and 26 of the first magnetic pole portion 24 has a cross-sectional shape orthogonal to the axis A of the rotation axis 3 as a whole. It is not a concentric circle with a center.

(Second rotor core 30)
As shown in FIG. 9, the radially outer circumferential surface f2 of the second magnetic pole portion 34 of the second claw-shaped magnetic pole 32 has a concentric circular arc surface in which the axial orthogonal cross-sectional shape is centered on the central axis O of the rotating shaft 3. In addition, there are two grooves, a first auxiliary groove 35 and a second auxiliary groove 36, on the radially outer peripheral surface f2.

  More specifically, as shown in FIG. 9, a straight line passing through the intermediate position in the circumferential direction of the second magnetic pole portion 34 from the central axis O of the rotating shaft 3 on the radial outer peripheral surface f <b> 2 of the second magnetic pole portion 34. The center line L2. Straight lines extending from the central axis O located at an angle θ2 in the clockwise direction and the counterclockwise direction with respect to the center line L2 are defined as a first straight line L2a and a second straight line L2b, respectively. Here, the angle θ2 was obtained using the following arithmetic expression based on the period φ of the cogging torque (detent torque) in the same manner as described above.

θ2 = (1/2 + n) · φ
Note that n is an integer, and in this embodiment, n = 0. The period φ of the cogging torque is 15 (= 360/24) degrees as described above.

Therefore, the angle θ2 is 7.5 (= 15/2) degrees, which is the same as the angle θ1.
Then, on the radially outer peripheral surface f2, the first straight line L2a and the second straight line L2b, which are respectively displaced by 7.5 degrees in the clockwise direction and the counterclockwise direction 8 around the center line L2, are used as intermediate positions in the circumferential direction. Grooves having a certain width are recessed in the axial direction.

  And the groove | channel which makes the 1st straight line L2a the circumferential direction intermediate position is the 1st auxiliary groove 35, and the groove | channel which makes the 2nd straight line L2b the circumferential direction intermediate position is the 2nd auxiliary groove 36 on the contrary. Therefore, the angle formed by the first auxiliary groove 35 and the second auxiliary groove 36 around the central axis O of the rotary shaft 3 coincides with the cogging torque period φ (= 15 degrees).

  That is, the angle formed by the center line L2 and the first straight line L2a and the angle formed by the center line L2 and the second straight line L2b are both a half period (= 7.5 degrees) of the period φ of the cogging torque. The second auxiliary groove 36 is formed at a symmetrical position with the center line L2 as the axis of symmetry.

  The first and second auxiliary grooves 35, 36 are formed in a U-shaped cross section in the direction perpendicular to the axis, and the bottom surfaces 35a, 36a are flat, and are perpendicular to the side surfaces extending from the outside in the radial direction from both sides. Is formed.

  Therefore, since the bottom surfaces 35 a and 36 a of the first and second auxiliary grooves 35 and 36 have a planar shape, the cross-sectional shape in the direction perpendicular to the axis does not become a concentric arc centered on the central axis O of the rotation shaft 3. As a result, the radial outer peripheral surface f2 including the bottom surfaces 35a and 36a of the first and second auxiliary grooves 35 and 36 of the second magnetic pole portion 34 has a cross-sectional shape orthogonal to the axis A of the rotation axis 3 as a whole. It is not a concentric circle with a center.

  The second rotor core 30 is disposed between the first claw-shaped magnetic poles 22 to which the second claw-shaped magnetic poles 32 respectively correspond. At this time, the second rotor core 30 is arranged such that the field magnet 40 is disposed (clamped) between the first core base 21 and the second core base 31 in the axial direction as in the first embodiment. The first rotor core 20 is assembled.

Next, the operation of the embodiment configured as described above will be described below.
Now, in the brushless motor M, when a three-phase power supply voltage is applied to each phase winding 13u, 13v, 13w of the stator core 10 to form a rotating magnetic field on the stator 2, it is fixed to the rotating shaft 3 arranged inside the stator 2. The rotor 4 thus rotated rotates based on the rotating magnetic field.

  When the application of the three-phase power supply voltage to each phase winding 13u, 13v, 13w is stopped, the rotating magnetic field disappears and the rotor 4 stops rotating. At this time, in the rotor 4, the magnetic flux that the first magnetic pole portion 24 of the first rotor core 20 flows into the teeth 11 of the stator core 10 and the magnetic flux that flows from the teeth 11 of the stator core 10 into the second magnetic pole portions 34 of the second rotor core 30 are the most. Stop at the pivot position where it becomes stable.

  In the same manner as in the first embodiment, this stop position is set every other one of the first and second magnetic pole portions 24 and 34 in which the radial outer peripheral surface f1 (radial outer peripheral surface f2) is located outside. It faces the inner peripheral surface 11 a of the tooth 11.

  In this state, when the rotor 4 (rotating shaft 3) is rotated, the radially outer circumferential surface f1 of the first magnetic pole portion 24 moves in the circumferential direction with respect to the radially inner circumferential surface 11a of the teeth 11 facing each other. .

At this time, since the tooth-side auxiliary groove 15 is formed on the inner peripheral surface 11a of the tooth 11, a holding force (detent torque T1) works as in the first embodiment.
In addition, since the first and second auxiliary grooves 25 and 26 are formed on the radially outer peripheral surface f1 of the first magnetic pole portion 24, the axial orthogonal cross-sectional shape as a whole is the central axis O of the rotary shaft 3. It does not become a concentric circle centered on. Similarly, since the first and second auxiliary grooves 35 and 36 are formed on the radially outer peripheral surface f2 of the second magnetic pole portion 34, the axial orthogonal cross-sectional shape as a whole is the central axis O of the rotary shaft 3. It does not become a concentric circle centered on.

  For this reason, the change in magnetic flux accompanying the movement is much greater than the radial outer peripheral surfaces f1 and f2 of the first and second magnetic pole portions 24 and 34 of the first embodiment, which are concentric circles centered on the central axis of the rotating shaft 3. Become bigger. As a result, the change of the magnetic field becomes very large, and the holding force (detent torque) becomes large.

  Moreover, the first auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are formed at symmetrical positions with the center lines L1 and L2 as the symmetry axes, respectively. Accordingly, the rotor 4 (rotating shaft 3) has the same holding force (detent torque) in any rotation direction.

  That is, the angle formed by the first auxiliary groove 25 (first straight line L1a) and the second auxiliary groove 26 (second straight line L1b) is formed to coincide with the period φ (= 15 degrees) of the cogging torque. Similarly, the angle formed by the first auxiliary groove 35 (first straight line L2a) and the second auxiliary groove 36 (second straight line L2b) is formed so as to coincide with the period φ (= 15 degrees) of the cogging torque.

  Accordingly, the holding force (detent torque) when the first auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are formed is the holding force when the first auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are not provided. Since the force (detent torque) is in phase, it increases.

  As a result, the holding force (detent torque T1) based on the tooth side auxiliary groove 15 formed on the inner peripheral surface 11a of the tooth 11, the first auxiliary grooves 25, 35 and the second auxiliary formed on the radial outer peripheral surfaces f1, f2. The holding force based on the grooves 26 and 36 (detent torque Tb (see FIG. 10)) is superimposed. Therefore, the holding force (detent torque T2 (see FIG. 10)) is larger than the holding force (detent torque T1) of the first embodiment.

  FIG. 10 shows the detent torque T2 when the teeth side auxiliary groove 15, the first auxiliary grooves 25 and 35, and the second auxiliary grooves 26 and 36 formed by experiments are formed. Note that the detent torque Tb shown in FIG. 10 does not form the teeth side auxiliary grooves 15 formed on the inner peripheral surface 11a of the teeth 11, and the first auxiliary grooves 25 and 35 and the second auxiliary grooves on the radially outer peripheral surfaces f1 and f2. The detent torque generated when forming 26 and 36 is shown.

  Thus, as is apparent from FIG. 10, the detent torque when auxiliary grooves are formed on the inner peripheral surface 11a of the tooth 11 and the radially outer peripheral surfaces f1 and f2 of the first and second magnetic pole portions 24 and 34, respectively. T2 is much larger than the detent torque Ta when the auxiliary grooves are not formed on the inner peripheral surface 11a of the tooth 11 and the radially outer peripheral surfaces f1 and f2 of the first and second magnetic pole portions 24 and 34. I understand. Moreover, it can be seen that it is larger than the detent torque T1 of the first embodiment.

Next, in addition to the effect of 1st Embodiment, the said embodiment has the following effects.
(1) According to the present embodiment, the radially outer peripheral surfaces f1 and f2 of the first and second claw-shaped magnetic pole portions 22 and 32 are first symmetrically positioned on both sides in the circumferential direction with the center lines L1 and L2 as the centers. Since the auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are formed, the detent torque can be increased and the holding force of the brushless motor M in the stationary state can be increased.

  (2) According to the present embodiment, the first auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are such that the angles θ1 and θ2 formed with the center lines L1 and L2 are the cogging torque period (angle φ), respectively. Since it is formed at a position having a half cycle (= φ / 2 = 7.5 degrees), the largest total detent torque Tc can be generated.

  In addition, since the first auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are formed in line-symmetric positions, in the brushless motor M that can rotate forward and backward, in any rotation direction of the rotor 4 (rotating shaft 3). Can also generate the same holding force (detent torque).

In addition, you may change the said embodiment as follows.
In each of the above-described embodiments, one tooth-side auxiliary groove 15 formed on the inner peripheral surface 11a of each tooth 11 is formed such that the circumferential center position of the bottom surface 15a coincides with the center line Lk. This may be performed by biasing the teeth side auxiliary groove 15 in the circumferential clockwise direction or the counterclockwise direction around the center line Lk.

In this case, when the angle formed with the center line Lk from the center axis O of the rotation axis that intersects the center position in the circumferential direction of the radially inner peripheral surface of the tooth 11 is θs,
− (360 / φ) / (Nr / 2) ≦ θs ≦ (360 / φ) / (Nr / 2)
The detent torque becomes larger when the teeth side auxiliary grooves 15 are not formed on the inner peripheral surface 11a.

  Here, φ is the period φ of the cogging torque, and in the above embodiment, 360 is divided by the least common multiple of the number of magnetic poles of the rotor 4 and the number of slots of the stator 2, so φ = 15 (= 360/24) degrees.

  As a result, when it is formed at a position in the range of −24 / (Nr / 2) ≦ θs ≦ 24 / (Nr / 2), the detent torque becomes larger when the tooth side auxiliary groove 15 is not formed on the inner peripheral surface 11a.

  Here, Nr is the number of magnetic poles of the rotor 4. Therefore, Nr / 2 = 8/2 = 4. Therefore, if it is set in the range of −6 degrees ≦ θs ≦ 6 degrees, the detent torque increases depending on the case where the teeth side auxiliary groove 15 is not formed on the inner peripheral surface 11a.

  In each of the above embodiments, the teeth side auxiliary groove 15 is formed on the inner peripheral surface 11 a of the tooth 11, and the inner peripheral surface 11 a as a whole has a concentric circle whose cross section in the axis orthogonal direction is centered on the central axis O of the rotating shaft 3. It was made not to become. For example, the inner circumferential surface 11a of the tooth 11 is made to have an elliptical cross-sectional shape or an orthogonal cross-sectional shape of a V-groove, and the axial cross-sectional shape is the center of the rotating shaft 3 as a whole. You may implement so that it may not become a concentric circle centering on the axis line O. FIG.

  In each of the above embodiments, one tooth side auxiliary groove 15 is formed on the inner peripheral surface 11 a of the tooth 11. This may be performed by forming a plurality of teeth side auxiliary grooves 15 on the inner peripheral surface 11a. In this case, the same holding force (detent torque) can be generated in any rotational direction of the rotor 4 by providing the center line Lk as a symmetric axis at line symmetric positions on both sides in the circumferential direction. In this configuration, of course, the teeth side auxiliary groove 15 may be formed on the inner peripheral surface 11a on the center line Lk.

  In the second embodiment, the first auxiliary grooves 25 and 35 and the second auxiliary grooves 26 and 36 are provided on the radially outer circumferential surfaces f1 and f2 of the first and second claw-shaped magnetic pole portions 22 and 32, respectively. They were formed at line symmetrical positions on both sides in the circumferential direction with L1 and L2 as the center. That is, as shown in FIG. 9, in the first claw-shaped magnetic pole portion 22, the first and second auxiliary grooves 25 and 26 are formed at positions intersecting the first and second straight lines L1a and L1b, respectively. Further, in the second claw-shaped magnetic pole portion 32, first and second auxiliary grooves 35 and 36 are formed at positions intersecting the first and second straight lines L2a and L2b, respectively.

  With reference to the first and second straight lines L1a and L1b of the first claw-shaped magnetic pole 22 and the first and second straight lines L2a and L2b of the second claw-shaped magnetic pole 32, respectively, You may carry out by forming an auxiliary groove, respectively.

  More specifically, for the first straight line L1a in the first claw-shaped magnetic pole 22, a pair of auxiliary grooves are formed at positions that are symmetrical about the first straight line L1a in the circumferential clockwise direction or the counterclockwise direction. . In addition, a pair of auxiliary grooves are formed at positions that are symmetrical about the second straight line L1b in the circumferential clockwise direction or the counterclockwise direction with respect to the second straight line L1b.

  Similarly, with respect to the first straight line L2a in the second claw-shaped magnetic pole 32, a pair of auxiliary grooves are formed at positions that are line-symmetrical in the circumferential clockwise direction or counterclockwise direction around the first straight line L2a. In addition, a pair of auxiliary grooves are formed in the second straight line L2b of the second claw-shaped magnetic pole 32 at positions that are line symmetric in the circumferential clockwise direction or the counterclockwise direction around the second straight line L2b.

  At this time, the angle θr formed between the straight line extending from the central axis O intersecting the circumferential center position of each pair of auxiliary grooves and the corresponding straight lines L1a, L1b, L2a, L2b is the same. The angle θr is set so that the following relational expression is established.

(1/4 + n) · φ <θr <(3/4 + n) · φ
Here, n is an integer and n = 0.
Therefore, (1/4) · φ <θr <(3/4) · φ
It becomes. Φ is the period (angle) of the cogging torque, and φ = 15 degrees.

As a result, 3.75 degrees <θr <11.25 degrees. In this range, a pair of line-symmetric auxiliary grooves centering on the corresponding straight lines L1a, L1b, L2a, and L2b are formed.

  Therefore, also in this case, four auxiliary grooves are formed in the first and second claw-shaped magnetic poles 22 and 32, respectively, and the radial outer peripheral surfaces f1 and f2 of the first and second claw-shaped magnetic pole portions 22 and 32 are formed. f2 is not a concentric circle with the central axis O as the center, and the detent torque can be increased.

  The first claw-shaped magnetic pole 22 is formed with a pair of auxiliary grooves at line symmetrical positions around the first and second straight lines L1a, L1b, respectively, and the second claw-shaped magnetic pole 32 has the first and second straight lines L2a, L2a, A pair of auxiliary grooves was formed in a line-symmetric position around L2b. And since the period of the detent torque by four auxiliary grooves formed in the radial direction outer peripheral surface f1, f2 of the 1st and 2nd nail | claw-shaped magnetic pole parts 22 and 32 corresponds with a cogging torque, a big detent torque is pulled out. be able to.

  In the brushless motor M shown in the second embodiment, as shown in FIGS. 11 and 12, first and second back auxiliary magnets are provided on the radially inner peripheral surfaces f1b and f2b of the first and second magnetic pole portions 24, respectively. 51 and 52 may be provided, and the first and second interpole auxiliary magnets 53 and 54 may be arranged between the first claw-shaped magnetic pole 22 and the second claw-shaped magnetic pole 32 in the circumferential direction.

  More specifically, as shown in FIG. 12B, the first back auxiliary magnet 51 is the radially inner peripheral surface f1b of the first magnetic pole portion 24, the outer peripheral surface 31c of the second core base 31, and the field magnet. The magnet 40 is disposed in a space formed by the outer peripheral surface 40 c of the magnet 40 and the surface of the first base 23 on the second rotor core 30 side. 12A, the first back auxiliary magnet 51 is the radially inner peripheral surface f2b of the second magnetic pole portion 34, and includes the outer peripheral surface 21c of the first core base 21 and the field magnet 40. Are disposed in a space formed by the outer peripheral surface 40c of the second base portion 33 and the surface of the second base portion 33 on the first rotor core 20 side.

  The first back auxiliary magnet 51 has a first claw-shaped magnetic pole on the side in contact with the radially inner circumferential surface f1b of the first claw-shaped magnetic pole 22 (first magnetic pole portion 24) in order to reduce the leakage magnetic flux at that portion. 22 is magnetized in the radial direction so that the side that contacts the second core base 31 becomes the S pole having the same polarity as the second core base 31. The second back auxiliary magnet 52 has a second claw-shaped magnetic pole on the side contacting the radially inner circumferential surface f2b of the second claw-shaped magnetic pole 32 (second magnetic pole portion 34) in order to reduce the leakage magnetic flux at that portion. The S pole having the same polarity as 32 is magnetized in the radial direction so that the side in contact with the first core base 21 becomes the N pole having the same polarity as the first core base 21.

  On the other hand, as shown in FIGS. 12A and 12B, the first interpole auxiliary magnet 53 includes one circumferential end face 22 a of the first claw-shaped magnetic pole 22 and the circumferential end face of the first back auxiliary magnet 51. And the flat surface formed by the other circumferential end surface 32 b of the second claw-shaped magnetic pole 32 and the circumferential end surface of the second back auxiliary magnet 52. The second interpole auxiliary magnet 54 includes a flat surface formed by the other circumferential end face 22b of the first claw-shaped magnetic pole 22 and a circumferential end face of the first back auxiliary magnet 51, and a second claw-shaped magnetic pole. 32 is arranged between one circumferential end surface 32 a of 32 and a flat surface formed by the circumferential end surface of the second back auxiliary magnet 52.

  The first and second interpole auxiliary magnets 53 and 54 have the same magnetic poles as the first and second claw-shaped magnetic poles 22 and 32 (the first claw-shaped magnetic pole 22 side is the N pole, and the second claw The magnetic pole 32 is magnetized in the circumferential direction so that the side of the magnetic pole 32 becomes the S pole.

  Thus, in the brushless motor M shown in FIGS. 11 and 12, the first and second back auxiliary magnets 51 and 52 and the first and second interpole auxiliary magnets 53 and 54 are provided, so that the amount of magnetic flux is increased. Since the detent torque increases, the detent torque can be increased, and the holding force of the brushless motor M in the stationary state can be increased.

  In the above embodiments, the brushless motor M has 8 poles and 12 slots. This may be applied to a 2N pole / 3N throttle system (where N is a natural number) brushless motor such as a 10 pole / 15 slot brushless motor.

  DESCRIPTION OF SYMBOLS 1 ... Motor housing, 2 ... Stator, 3 ... Rotating shaft, 4 ... Rotor, 10 ... Stator core, 11 ... Teeth, 11a ... Inner peripheral surface, 12 ... Slot, 13u ... U-phase winding, 13v ... V-phase winding, 13w ... W-phase winding, 15 ... Teeth side auxiliary groove, 15a ... Bottom, 20 ... First rotor core, 20a ... Through hole, 21 ... First core base, 21a ... Opposing surface, 21b ... Anti-opposing surface, 21c ... Outer circumference Surface, 22 ... first claw-shaped magnetic pole, 22a, 22b ... end face, 22c ... tip face, 23 ... first base, 24 ... first magnetic pole part, 25, 26 ... first and second auxiliary grooves (rotor side auxiliary grooves) ), 25a, 26a ... bottom surface, 30 ... second rotor core, 30a ... through hole, 31 ... second core base, 31a ... opposing surface, 31b ... anti-opposing surface, 31c ... outer peripheral surface, 32 ... second claw-shaped magnetic pole, 32a, 32b ... end face, 32c ... tip face, 33 2nd base, 34 ... 2nd magnetic pole part, 35, 36 ... 1st and 2nd auxiliary groove, 35a, 36a ... Bottom, 40 ... Field magnet, 40a, 40b ... Side, 40c ... Outer peripheral surface, 41 ... Through-hole , 51, 52 ... first and second back auxiliary magnets (back side auxiliary magnets), 53, 54 ... first and second interpole auxiliary magnets (interpole auxiliary magnet), M ... brushless motor, O ... central axis, f1 , F2 ... radial outer peripheral surface, f1b, f2b ... radial inner peripheral surface, Lk, L1, L2 ... center line, L1a, L2a ... first straight line, L1b, L2b ... second straight line, θ1, θ2, φ ... angle , T1, T2, Ta, Tb ... detent torque.

Claims (9)

A plurality of first claw-shaped magnetic poles project outwardly in the radial direction on the outer peripheral surface of a circular first core base that rotates integrally with the rotation shaft about the rotation shaft, and the tip is bent. A first rotor core formed extending in the axial direction;
A plurality of second claw-shaped magnetic poles project outwardly in the radial direction on the outer peripheral surface of a circular second core base that rotates integrally with the rotation shaft about the rotation shaft, and the tips thereof are bent. Extending in the axial direction, and each second claw-shaped magnetic pole is disposed between the first claw-shaped magnetic poles adjacent to each other in the circumferential direction, and a second rotor core,
The rotating shaft is integrally rotated with the rotating shaft as a rotation center and is disposed between the first core base of the first rotor core and the second core base of the second rotor core, and is magnetized along the axial direction. A rotor provided with a field magnet that causes each first claw-shaped magnetic pole to function as a first magnetic pole and causes each second claw-shaped magnetic pole to function as a second magnetic pole;
A stator core disposed on the outer side of the rotor, the inner circumferential surface of which has a plurality of teeth facing the outer circumferential surface of the first and second claw-shaped magnetic poles at equal intervals in the circumferential direction;
A motor comprising a stator that is wound around each of the teeth and includes a winding that generates a rotating magnetic field when energized,
The motor according to claim 1, wherein a cross-sectional shape in a direction perpendicular to the axis of the radially inner peripheral surface of the teeth is not a concentric circle centering on a central axis of the rotating shaft. The motor according to claim 1,
A teeth side auxiliary groove extending along the axial direction is formed on the radially inner circumferential surface of the teeth, and the axial orthogonal cross-sectional shape of the radially inner circumferential surface of the teeth is a concentric circle centering on the central axis of the rotating shaft. A motor characterized by not becoming. The motor according to claim 2,
When the period of the cogging torque is φ and the number of magnetic poles of the rotor is Nr, the teeth side auxiliary groove is a center line from the central axis of the rotating shaft that intersects the circumferential center position of the radially inner circumferential surface of the teeth. When the angle between is θs, in the circumferential direction,
A motor characterized by being formed at a position in a range of (360 / φ) / (Nr / 2) ≦ θs ≦ (360 / φ) / (Nr / 2). The motor according to claim 3, wherein
The tooth-side auxiliary groove has a U-shaped cross-section in the direction perpendicular to the axis, and is formed along the axial direction at one central position in the circumferential direction of the radially inner circumferential surface of the teeth. In the motor according to any one of claims 1 to 4,
The motor of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole, wherein the cross-sectional shape of the radially outer circumferential surface of the first claw-shaped magnetic pole is not a concentric circle centered on the central axis of the rotating shaft. In the motor according to any one of claims 1 to 5,
A rotor side auxiliary groove extending along the axial direction is formed on the radially outer peripheral surfaces of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole, and the radially outer peripheral surfaces of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole. The motor is characterized in that the cross-sectional shape in the direction perpendicular to the axis does not become a concentric circle centered on the central axis of the rotating shaft. The motor according to claim 6, wherein
The rotor side auxiliary groove is formed along the axial direction from the circumferential center position of the radially outer circumferential surface of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole to a position half the period of the cogging torque on both circumferential sides. A motor characterized by comprising one auxiliary groove and a second auxiliary groove. In the motor according to any one of claims 1 to 7,
The rotor is magnetized between the first claw-shaped magnetic pole and the second claw-shaped magnetic pole adjacent in the circumferential direction so as to be the same as the first claw-shaped magnetic pole and the second claw-shaped magnetic pole. A motor comprising an auxiliary magnet. The motor according to any one of claims 1 to 8,
The rotor is magnetized on the radially inner circumferential surface side of the first claw-shaped magnetic pole and the second claw-shaped magnetic pole so as to be the same as the first claw-shaped magnetic pole and the second claw-shaped magnetic pole, respectively. A motor characterized in that a back auxiliary magnet is arranged.