JP2014155381A - Rotor, and brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor the rotational position (angle) of which can be detected with high accuracy.SOLUTION: A rotor 21 includes a first rotor core 31 where a plurality of first claw-shaped magnetic poles 31b are formed on the outer periphery of a first core base 31a and a second rotor core 32 where a plurality of second claw-shaped magnetic poles 32b are formed on the outer periphery of a second core base, a field magnet arranged between the axial directions of the first and second core bases, and making the first claw-shaped magnetic pole 31b function as a first magnetic pole and the second claw-shaped magnetic pole 32b function as a second magnetic pole by being magnetized in the axial direction, and an annular sensor magnet 42 provided at a position shifted from the first and second rotor cores 31, 32 in the axial direction, with the axial magnetization directions being differentiated from each other in the circumferential direction. The sensor magnet 42 is formed to have an inner diameter larger than the outer diameter of the first core base 31a, and is provided so that the magnetic pole on the side facing the first and second claw-shaped magnetic poles 31b, 32b matches that of the claw-shaped magnetic pole.

Description

  The present invention relates to a rotor and a brushless motor.

  The rotor of the brushless motor includes two rotor cores that are combined with each other having a plurality of claw-shaped magnetic poles in the circumferential direction, and a field magnet that is disposed between them and magnetized in the axial direction. There is a so-called permanent magnet field Landel-type rotor that causes the different magnetic poles to function alternately (see, for example, Patent Document 1).

  In a brushless motor, the rotational position (angle) of the rotor is detected, and a rotating magnetic field is generated by supplying a driving current to the windings of the stator according to the rotational position, and the rotor is rotationally driven by the rotating magnetic field. Is done.

JP 2012-115085 A

  By the way, in the brushless motor, as a configuration for detecting the rotational position of the rotor, for example, sensor magnets having magnetic poles (N pole and S pole) which are alternately different in the circumferential direction are provided side by side in the axial direction of the rotor core. There is a configuration in which a magnetic sensor for detecting the magnetic field is provided on the side facing the sensor magnet in the axial direction.

  However, in the rotor, since the field magnet is magnetized in the axial direction, the leakage flux in the axial direction from the rotor core is superimposed on the magnetic flux from the sensor magnet, and the detection signal detected by the magnetic sensor There was a problem that the rotational position (angle) of the rotor could not be detected with high accuracy without switching the levels at equal pitches. This causes a deviation from the optimum timing of the drive current supplied to the stator windings, which in turn causes a decrease in output and a deterioration in vibration noise.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotor and a brushless motor that can detect a rotational position (angle) with high accuracy.

  Each of the rotors that solve the above-described problems has a plurality of claw-shaped magnetic poles projecting radially outward at equal intervals on the outer periphery of a substantially disk-shaped core base and extending in the axial direction. Are arranged between the first and second rotor cores in which the claw-shaped magnetic poles are alternately arranged in the circumferential direction while being opposed to each other and the axial direction of the core bases, and are magnetized in the axial direction, whereby the first rotor core A field magnet that causes the claw-shaped magnetic pole of the second rotor core to function as the first magnetic pole and a function of the claw-shaped magnetic pole of the second rotor core as the second magnetic pole, and a position shifted in the axial direction from the first and second rotor cores Provided with an annular sensor magnet in which the axially magnetized directions are alternately varied in the circumferential direction, and the sensor magnet has an inner diameter that is larger than an outer diameter of the core base. As it is formed large, Side of the magnetic pole facing the Kitsumejo pole is provided so as to coincide with the magnetic pole of the claw-shaped magnetic poles.

  According to this configuration, the sensor magnet is formed so that its inner diameter is larger than the outer diameter of the core base, and the magnetic pole on the side facing the claw-shaped magnetic pole coincides with the magnetic pole of the claw-shaped magnetic pole. The leakage flux in the axial direction from the claw-shaped magnetic pole to the sensor magnet is suppressed. As a result, the magnetic flux from the sensor magnet to the magnetic sensor provided in the axial direction opposite to the claw-shaped magnetic pole of the sensor magnet is suppressed from being affected by the leakage magnetic flux from the claw-shaped magnetic pole. It is possible to detect the rotational position (angle) of this with high accuracy.

  In the rotor, the sensor magnet is magnetized in the axial direction in different circumferential directions at equal angular intervals, and each circumferential center of the magnetic pole on the side facing the claw-shaped magnetic pole is in each circumferential direction of the claw-shaped magnetic pole. It is preferable to be provided so as to coincide with the center.

  According to this configuration, the sensor magnets are different in the direction magnetized in the axial direction at equal angular intervals in the circumferential direction, and the circumferential center of the magnetic pole on the side facing the claw-shaped magnetic pole is the circumferential center of the claw-shaped magnetic pole. Therefore, the level of the detection signal detected by the magnetic sensor can be switched at an equal pitch.

  A brushless motor that solves the above problem includes the rotor, a stator that generates a rotating magnetic field, and a magnetic sensor that is provided in the axial direction opposite to the claw-shaped magnetic pole of the sensor magnet.

  According to this configuration, the above effect can be obtained in the brushless motor.

  In the rotor and the brushless motor of the present invention, the rotational position (angle) can be detected with high accuracy.

Sectional drawing of the brushless motor in one Embodiment. The partial cross section perspective view of the brushless motor in the same form. The partial top view of the rotor in the same form. The partial cross section figure of the brushless motor in the form. Sectional drawing for demonstrating the rotor in another example. Sectional drawing for demonstrating the rotor in another example. Sectional drawing for demonstrating the rotor in another example. Sectional drawing for demonstrating the rotor in another example.

Hereinafter, an embodiment of a brushless motor will be described with reference to FIGS.
As shown in FIG. 1, a motor case 12 of a brushless motor 11 has a cylindrical housing 13 formed in a bottomed cylindrical shape and a front side (left side in FIG. 1) opening of the cylindrical housing 13 closed. And a front end plate 14.

  As shown in FIG. 1, a stator 16 is fixed to the inner peripheral surface of the cylindrical housing 13. The stator 16 is wound around an armature core 17 having a plurality of (in this embodiment, 12) teeth 17a serving as concentrated winding teeth extending radially inward and a tooth 17a of the armature core 17 via an insulator 18. Winding 19 is provided. The stator 16 generates a rotating magnetic field when a drive current is supplied from the external control circuit S to the winding 19.

  As shown in FIG. 1, the rotor 21 of the brushless motor 11 has a rotating shaft 22 and is disposed inside the stator 16. The rotating shaft 22 is a non-magnetic metal shaft, and is rotatably supported by bearings 23 and 24 supported by the bottom portion 13a of the cylindrical housing 13 and the front end plate 14.

As shown in FIGS. 1 and 2, the rotor 21 includes first and second rotor cores 31 and 32 that are fitted onto the rotary shaft 22, and an annular magnet 33 as a field magnet.
The first rotor core 31 has a plurality of (four in the present embodiment) first claw-shaped magnetic poles 31b projecting radially outwardly at equal intervals on the outer periphery of a substantially disk-shaped first core base 31a. It extends in the direction.

  The second rotor core 32 has the same shape as the first rotor core 31, and a plurality of second claw-shaped magnetic poles 32b are projected radially outwardly at equal intervals on the outer periphery of a substantially disk-shaped second core base 32a. And extending in the axial direction. The second rotor core 32 is arranged such that each second claw-shaped magnetic pole 32b is disposed between the first claw-shaped magnetic poles 31b adjacent to each other in the circumferential direction, and between the first core base 31a and the second core base 32a. The annular magnet 33 is assembled to the first rotor core 31 so as to be disposed (clamped) in the axial direction. In the present embodiment, the first and second core bases 31a and 32a are respectively fixed to the annular magnet 33 with an adhesive.

  The annular magnet 33 causes the first claw-shaped magnetic pole 31b to function as a first magnetic pole (N pole in the present embodiment), and causes the second claw-shaped magnetic pole 32b to function as a second magnetic pole (S pole in the present embodiment). Thus, it is magnetized in the axial direction. That is, the rotor 21 of the present embodiment is a so-called Landell type rotor using an annular magnet 33 as a field magnet. In the rotor 21, four first claw-shaped magnetic poles 31b that are N poles and four second claw-shaped magnetic poles 32b that are S poles are alternately arranged in the circumferential direction, and the number of poles is eight (the number of pole pairs). Is 4). That is, in the present embodiment, the number of poles of the rotor 21 is set to “8”, and the number of teeth 17a of the stator 16 is set to “12”.

  In addition, the rotor 21 of the present embodiment is provided on the radially inner side (rear surface) of the first and second claw-shaped magnetic poles 31b and 32b, and the rear surface is magnetized in the radial direction so as to suppress leakage (short circuit) magnetic flux in the portion. An auxiliary magnet 34 is provided.

  Further, the rotor 21 of the present embodiment is provided between the first and second claw-shaped magnetic poles 31b and 32b in the circumferential direction, and the interpole magnet 35 magnetized in the circumferential direction to suppress the leakage magnetic flux of the portion. It has.

  As shown in FIG. 1, the rotor 21 is provided with a sensor magnet 42 via a substantially disc-shaped magnet fixing member 41. Specifically, the magnet fixing member 41 includes a disc portion 41b having a boss portion 41a formed at the center, and a cylinder portion 41c extending in a cylindrical shape from the outer edge of the disc portion 41b. An annular sensor magnet 42 is fixed so as to come into contact with the peripheral surface and the surface of the disc portion 41b. And the magnet fixing member 41 is a position shifted in the axial direction from the first and second rotor cores 31 and 32, and the boss portion 41 a is fitted on the rotary shaft 22 on the side close to the first rotor core 31. Yes. In other words, the magnet fixing member 41 (sensor magnet 42) of the present embodiment is fixed to the rotating shaft 22 at a position where the first rotor core 31 is sandwiched between the second rotor core 32.

  In the front end plate 14, a Hall IC 43 as a magnetic sensor is provided at a position facing the sensor magnet 42 in the axial direction. In other words, the Hall IC 43 is fixed to the front end plate 14 at a position where the sensor magnet 42 is sandwiched between the first rotor core 31. The Hall IC 43 outputs an H level detection signal and an L level detection signal to the control circuit S when sensing the N pole and S pole magnetic fields.

  Here, as shown in FIGS. 3 and 4, the sensor magnet 42 is formed such that the inner diameter thereof is larger than the outer diameters of the first and second core bases 31 a and 32 a and the annular magnet 33. The magnetic poles on the side facing the second claw-shaped magnetic poles 31b and 32b are provided so as to coincide with the magnetic poles of the claw-shaped magnetic poles.

  Specifically, the sensor magnet 42 is configured such that the direction magnetized in the axial direction is alternately changed in the circumferential direction, and in this embodiment, the direction magnetized in the axial direction at equiangular (45 °) intervals. It is different. In FIG. 3, the magnetic poles on the front side of the sheet of the sensor magnet 42 are shown with N and S symbols. As shown in FIG. 4, the sensor magnet 42 has a magnetic pole on the side facing the first claw-shaped magnetic pole 31 b at the position in the circumferential direction facing the first claw-shaped magnetic pole 31 b functioning as the N pole. Thus, the magnetic poles on the non-opposing side (the front side in FIG. 3) are provided to be the S poles. Further, the sensor magnet 42 is located at the circumferential position facing the second claw-shaped magnetic pole 32b functioning as the S pole, and the magnetic pole on the side facing the second claw-shaped magnetic pole 32b is the S pole and the magnetic pole on the side not facing the second magnet. Are provided so as to be N poles. Further, in the sensor magnet 42 of the present embodiment, the respective circumferential centers of the magnetic poles on the side facing the first and second claw-shaped magnetic poles 31b and 32b are in the circumferential directions of the first and second claw-shaped magnetic poles 31b and 32b. It is provided so as to coincide with the center.

Next, the operation of the brushless motor 11 configured as described above will be described.
When a three-phase drive current is supplied from the control circuit S to the winding 19, a rotating magnetic field is generated in the stator 16, and the rotor 21 is driven to rotate. At this time, as the sensor magnet 42 facing the Hall IC 43 rotates, the level of the detection signal output from the Hall IC 43 is switched according to the rotation angle (position) of the rotor 21, and the control circuit S is based on the detection signal. To the winding 19 is supplied with a three-phase drive current that switches at an optimal timing. As a result, a rotating magnetic field is generated satisfactorily, and the rotor 21 is driven to rotate continuously.

Next, the characteristic effects of the above embodiment will be described below.
(1) The sensor magnet 42 has an inner diameter larger than the outer diameter of the first and second core bases 31a and 32a, and a magnetic pole on the side facing the first and second claw-shaped magnetic poles 31b and 32b. Since it is provided so as to coincide with the magnetic pole of the claw-shaped magnetic pole, the leakage flux in the axial direction from the first and second claw-shaped magnetic poles 31b and 32b to the sensor magnet 42 is suppressed. As a result, the magnetic flux from the sensor magnet 42 to the Hall IC 43 is suppressed from being affected by the leakage magnetic flux from the first and second claw-shaped magnetic poles 31b and 32b. As a result, the rotational position (angle) of the rotor 21 at the Hall IC 43. Can be detected with high accuracy.

  (2) The sensor magnet 42 is magnetized in the axial direction, and the circumferential direction of the magnetic poles on the side facing the first and second claw-shaped magnetic poles 31b and 32b is different at an equal angle (45 °) interval in the circumferential direction. The center is provided so as to coincide with the circumferential center of each of the first and second claw-shaped magnetic poles 31b and 32b. Thereby, the level of the detection signal detected by the Hall IC 43 can be switched at an equal pitch.

The above embodiment may be modified as follows.
-The 1st and 2nd rotor cores 31 and 32 of the said embodiment are externally fitted by the rotating shaft 22, and the rotating shaft 22 is press-fit only in the center hole of the 1st and 2nd core bases 31a and 32a. However, the present invention is not limited to this, and a cylindrical boss portion into which the rotary shaft 22 is press-fitted may be formed on the inner peripheral edge of the core base.

  For example, as shown in FIG. The claw-shaped magnetic poles (the first core base 31a is the first claw-shaped magnetic pole 31b and the second core base 32a is the second claw-shaped magnetic pole 32b) are arranged on the inner peripheral edges of the first and second core bases 31a and 32a in this example. ) In the same direction as the direction extending in the axial direction, i.e., the opposite direction, and an inwardly extending boss portion 51 into which the rotary shaft 22 is press-fitted is formed. In this example, the inner diameter of the annular magnet 33 is set to be substantially the same as the outer diameter of the inwardly extending boss part 51, and there is a gap between the inwardly extending boss parts 51.

  In this way, the axial press-fitting range can be widened, and the first and second rotor cores 31 and 32 can be firmly fixed to the rotary shaft 22 and in the opposite direction (external direction in the axial direction). Compared with the case where the extended boss part is provided, the arrangement space is not required outside the first and second core bases 31a and 32a.

  For example, as shown in FIG. In this example, the inner auxiliary for suppressing the leakage magnetic flux between the inwardly extending boss part 51 of the first rotor core 31 and the inwardly extending boss part 51 of the second rotor core 32 in the other example (see FIG. 5). A magnet 52 is provided. If it does in this way, the leakage magnetic flux between inwardly extending boss | hub parts 51 will be suppressed, and the fall of motor efficiency can be suppressed. The inner auxiliary magnet 52 may be a ferrite magnet or the like, or may be a bonded magnet, and in the case of a bonded magnet, the inner auxiliary magnet 52 can be provided in close contact with the inwardly extending boss portion 51 without requiring high dimensional accuracy. .

  For example, as shown in FIG. In this example, the inner auxiliary for suppressing the leakage magnetic flux between the inwardly extending boss part 51 of the first rotor core 31 and the inwardly extending boss part 51 of the second rotor core 32 in the other example (see FIG. 5). An inner auxiliary magnet portion 53 as a magnet is integrally formed with the annular magnet 33. If it does in this way, the leakage magnetic flux between inwardly extending boss | hub parts 51 will be suppressed, and the fall of motor efficiency can be suppressed.

  Further, for example, as shown in FIG. In this example, the inner peripheral edges of the first and second core bases 31a and 32a are formed while forming the inwardly extending boss part 54 in which the protruding amount in the axial direction of the inwardly extending boss part 51 in the other example (see FIG. 5) is reduced. Thus, an outwardly extending boss part 55 protruding in the opposite direction of the inwardly extending boss part 54 is formed.

  In this way, the axial press-fitting range can be widened, and the first and second rotor cores 31 and 32 can be firmly fixed to the rotary shaft 22 and in the opposite direction (external direction in the axial direction). Compared to the case where only the extended boss portion is provided, the arrangement space required outside the first and second core bases 31a and 32a can be reduced. In addition, while obtaining the same fixing strength, the distance between the inwardly extending boss parts 51 can be increased compared to the other example (see FIG. 5), and the leakage magnetic flux between the inwardly extending boss parts 51 can be reduced. can do.

  Of course, the above-described inwardly extending boss portion 51 is formed only on one of the first and second core bases 31a and 32a, or the axially extending direction is not provided without the inwardly extending boss portion 51. A boss portion may be provided.

  In the above embodiment, the back auxiliary magnet 34 is provided radially inward of the first and second claw-shaped magnetic poles 31b and 32b and magnetized in the radial direction. You may change to the rotor which is not equipped with.

  In the above embodiment, the interpole magnet 35 provided between each of the first and second claw-shaped magnetic poles 31b and 32b in the circumferential direction is provided. However, the present invention is not limited to this. You may change into the rotor which is not equipped with the interposition magnet 35. FIG.

The technical idea that can be grasped from the above embodiment will be described below.
(A) A plurality of claw-shaped magnetic poles projecting radially outward and extending in the axial direction on the outer periphery of each substantially disk-shaped core base, and claw while the core bases face each other. The claw-shaped magnetic poles of the first rotor core are arranged between the first and second rotor cores in which the magnetic poles are alternately arranged in the circumferential direction, and are magnetized in the axial direction between the core bases. And a field magnet that allows the claw-shaped magnetic pole of the second rotor core to function as a second magnetic pole, and the inner periphery of the core base has the claw-shaped A rotor characterized in that an inwardly extending boss portion is formed, which extends in the same direction as the magnetic pole extending in the axial direction and into which a rotating shaft is press-fitted.

  According to this configuration, the inner peripheral edge of the core base is formed with an inwardly extending boss portion that extends in the same direction as the axially extending direction of the claw-shaped magnetic pole and into which the rotary shaft is press-fitted. Compared to the case where a boss extending in the opposite direction is provided, the space for the press-fitting is not required outside the core base. .

  (B) In the rotor according to (A) above, an inner auxiliary for suppressing leakage magnetic flux between the inner boss portion of the first rotor core and the inner boss portion of the second rotor core. A rotor provided with a magnet.

  According to this configuration, since the inner auxiliary magnet for suppressing the leakage magnetic flux is provided between the inner boss portion of the first rotor core and the inner boss portion of the second rotor core, the inner boss portions are Leakage of magnetic flux between them is suppressed, and a decrease in motor efficiency can be suppressed.

  16 ... stator, 21 ... rotor, 31 ... first rotor core, 31a ... first core base (core base), 31b ... first claw-shaped magnetic pole (claw-shaped magnetic pole), 32 ... second rotor core, 32a ... second core base (Core base), 32b ... second claw-shaped magnetic pole (claw-shaped magnetic pole), 33 ... annular magnet (field magnet), 42 ... sensor magnet, 43 ... Hall IC 43 (magnetic sensor).

Claims (3)

A plurality of claw-shaped magnetic poles project radially outward and extend in the axial direction on the outer periphery of each substantially disk-shaped core base, and the claw-shaped magnetic poles are formed with the core bases facing each other. First and second rotor cores arranged alternately in the circumferential direction;
The claw-shaped magnetic poles of the first rotor core function as the first magnetic poles by being arranged between the axial directions of the core bases and magnetized in the axial direction, and the claw-shaped magnetic poles of the second rotor core are made to function as the first magnetic poles. A field magnet that functions as a second magnetic pole;
A rotor provided with annular sensor magnets provided at positions shifted in the axial direction from the first and second rotor cores and in which the directions magnetized in the axial direction are alternately varied in the circumferential direction;
The sensor magnet is formed such that its inner diameter is larger than the outer diameter of the core base, and the magnetic pole on the side facing the claw-shaped magnetic pole coincides with the magnetic pole of the claw-shaped magnetic pole. Rotor. The rotor according to claim 1, wherein
The sensor magnets are magnetized in the axial direction at equal angular intervals in the circumferential direction, and the respective circumferential centers of the magnetic poles facing the claw-shaped magnetic poles coincide with the circumferential centers of the claw-shaped magnetic poles. The rotor is provided as described above. The rotor according to claim 1 or 2,
A stator that generates a rotating magnetic field;
A brushless motor, comprising: a magnetic sensor provided in an axial direction opposite to the claw-shaped magnetic pole of the sensor magnet.