JP2014183694A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor capable of suppressing leakage magnetic flux and improving output characteristics.SOLUTION: When it is defined that a separation distance between a stator 16 and a pawl-like magnetic pole 31b in a diameter direction is A and a separation distance between first and second rotor cores 31, 32 and a york housing 13 (bottom 13a) in an axial direction is B, a range of 5.0≤B/A is set.

Description

  The present invention relates to a motor that houses a stator and a rotor in a case.

  Conventionally, a rotor core used in a motor has a rotor core that is combined with a plurality of claw-shaped magnetic poles in the circumferential direction, and field magnets are arranged between them to make the claw-shaped magnetic poles alternately different magnetic poles. A so-called permanent magnet field Landell-type rotor is known (for example, see Patent Document 1).

  In addition, in the Landel-type rotor, in order to increase the output of the motor, an interpole magnet for rectifying a magnetic path between alternately arranged claw-shaped magnetic poles has been proposed. (For example, refer to Patent Document 2). In such a motor, the rotor and the stator are housed in a case having a bottomed cylindrical yoke housing and an end frame provided at one end of the yoke housing.

Japanese Utility Model Publication No. 5-43749 JP 2012-115085 A

  By the way, in the motor as described above, the yoke housing made of magnetic material is positioned on the one axial end surface side of the rotor, and the resin end frame is positioned on the other axial end surface side of the rotor. In this case, a part of the magnetic flux from the field magnet of the rotor may leak to the case side (yoke housing side), leading to deterioration of output characteristics.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor capable of suppressing leakage magnetic flux and improving output characteristics.

  A motor that solves the above problems includes a stator core having a plurality of teeth extending in the circumferential direction in the circumferential direction, a stator having a winding wound around the teeth, and an outer peripheral portion of a substantially disk-shaped core base, etc. A plurality of claw-shaped magnetic poles projecting radially outward and extending in the axial direction at intervals, and first and second rotor cores having claw-shaped magnetic poles alternately arranged in the circumferential direction while facing each other's core base And 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 of the second rotor core A rotor having a field magnet that causes a magnetic pole to function as a second magnetic pole is housed in a case having a bottomed cylindrical magnetic housing and a lid that closes the opening of the yoke housing. Where the distance between the stator and the claw-shaped magnetic pole in the radial direction is A, and the distance between the first and second rotor cores and the yoke housing in the axial direction is B, 5.0 ≦ It becomes the range of B / A.

  According to this configuration, when the radial distance between the stator and the claw-shaped magnetic pole is A and the axial distance between the first and second rotor cores and the yoke housing is B, 5.0 ≦ B / A It is considered as a range. Here, FIG. 5 shows TN characteristics and TI characteristics when the B / A is changed, and FIG. 6 shows a current ratio when the B / A is changed at the rated load. In FIG. 5, a graph of the TI characteristic when B / A is “3” is indicated by a line Ti1, and a graph of the TI characteristic when B / A is “6” is indicated by a line Ti2. A graph of the TI characteristic when A is “9” is indicated by a line Ti3. In FIG. 5, the TN characteristic graph when B / A is “3” is indicated by a line Tn1, and the TN characteristic graph when B / A is “6” is indicated by a line Tn2. A graph of the TN characteristic when B / A is “9” is indicated by a line Tn3. In FIG. 6, the DC current with B / A of “6” is shown as 100%. As can be seen from FIG. 5, the larger the value of B / A, the higher the torque obtained with the same DC current. As can be seen from FIG. 6, when the B / A is less than “5”, the DC current is remarkably lowered, but when B / A is “5” or more, the decrease rate becomes moderate. Thus, by setting B / A to be “5” or more, the separation distance B in the axial direction between the first and second rotor cores and the yoke housing is set to the separation distance A in the radial direction between the stator and the claw-shaped magnetic pole. As a result, the leakage magnetic flux in the axial direction is reduced, so that the output characteristics (motor characteristics) are improved.

In the motor, it is preferable that a distance in the axial direction between the rotor core and the yoke housing is longer on a radially outer side than on a radially inner side.
According to this configuration, the distance between the rotor core and the yoke housing in the axial direction is increased on the outer side in the radial direction, which is a portion having a large surface area per circumference, so that the leakage magnetic flux can be more suitably reduced. Become.

  According to the motor of the present invention, leakage magnetic flux can be suppressed and output characteristics can be improved.

It is sectional drawing of the brushless motor in one Embodiment. It is a top view of the brushless motor in the same as the above. It is a perspective view of the rotor in the same as the above. It is sectional drawing of the rotor in the same as the above. It is a graph which shows the TN characteristic and TI characteristic when the separation distance A in the radial direction between the stator and the claw-shaped magnetic pole / the separation distance B in the axial direction between the rotor core and the yoke housing is changed. It is a graph which shows the ratio of the DC current in a rated load. It is explanatory drawing for demonstrating the bias | deviation of a detent torque. It is a graph for demonstrating the relationship between the separation distance A in the radial direction of the data and the claw-shaped magnetic pole / the separation distance B in the axial direction of the rotor core and the yoke housing, and the detent torque. It is sectional drawing of the brushless motor in another example.

Hereinafter, an embodiment of the motor will be described.
As shown in FIG. 1, a motor case 12 of a brushless motor 11 as a motor includes a yoke housing 13 formed in a substantially bottomed cylindrical shape, and an opening on the front side (left side in FIG. 1) of the yoke housing 13. And an end plate 14 for closing. The yoke housing 13 is made of, for example, magnetic iron. The end plate 14 is made of, for example, a non-magnetic resin material.

  As shown in FIG. 1, a stator 16 is fixed to the inner peripheral surface of the yoke housing 13. The stator 16 includes a stator core 17 having a plurality of teeth 17 a extending radially inward, and a winding 20 wound around the teeth 17 a of the stator core 17 via an insulator 19. The stator 16 generates a rotating magnetic field when a drive current is supplied from the external control circuit S to the winding 20.

As shown in FIG. 2, the stator core 17 has a total of 12 teeth 17a. Therefore, the number of slots 17b formed between the teeth 17a is also twelve.
As shown in FIG.2 and FIG.5, the teeth 17a are provided with the winding part 18a and the protrusion part 18b which protrudes in the circumferential direction both sides from the radial direction inner side edge part of the winding part 18a. In the winding portion 18a, the U-phase, V-phase, and W-phase windings 20 are wound in concentrated winding.

  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 13 a of the yoke housing 13 and the end plate 14.

  As shown in FIGS. 3 and 4, the rotor 21 includes first and second rotor cores 31 and 32 that are fixed to the rotating shaft 22 while the axial distance between the rotating shafts 22 is maintained by press-fitting the rotating shaft 22. And an annular magnet 33 as a field magnet interposed between the first rotor core 31 and the second rotor core 32 in the axial direction. Further, the rotor 21 includes back auxiliary magnets 34 and 35 and interpole magnets 36 and 37.

  As shown in FIGS. 3 and 4, the first rotor core 31 has a plurality of (five in the present embodiment) first claw-shaped magnetic poles 31 b on the outer periphery of the substantially disk-shaped first core base 31 a. Projecting outward in the radial direction and extending in the axial direction.

  As shown in FIGS. 3 and 4, the second rotor core 32 has the same shape as the first rotor core 31, and a plurality of second claws are arranged at equal intervals on the outer periphery of the substantially disk-shaped second core base 32 a. The magnetic pole 32b protrudes radially outward and extends in the axial direction. The first and second rotor cores 31 and 32 have the rotary shaft 22 press-fitted into their center holes, and the first and second core bases 31a and 32a have a distance in the axial direction outside (opposite sides) in advance. The rotary shaft 22 is press-fitted and fixed so as to have a set constant distance. At this time, the second rotor core 32 is arranged such that each of the second claw-shaped magnetic poles 32b is disposed between the first claw-shaped magnetic poles 31b adjacent in the circumferential direction, and 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) between the first rotor core 31 and the second rotor core 31.

  The annular magnet 33 is a magnet such as a ferrite magnet or a neodymium magnet, and is formed in an annular shape having a central hole, and functions as the first claw-shaped magnetic pole 31b as the first magnetic pole (N pole in the present embodiment). The second claw-shaped magnetic pole 32b is magnetized in the axial direction so as to function as a second magnetic pole (S pole in this embodiment). 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”. That is, the number of poles of the rotor 21 is 2n (where n is a natural number, 4 in the present embodiment), the number of slots 17b (slot number) is 3n, and the ratio of the number of poles to the number of slots is 2: 3. It is configured as follows.

  A back auxiliary magnet 34 is disposed between the back surface 31c (radially inner surface) of each first claw-shaped magnetic pole 31b and the outer peripheral surface 32d of the second core base 32a. The back auxiliary magnet 34 has a substantially fan-shaped cross section in the direction orthogonal to the axis, and the second core base 32a has a side that abuts on the back surface 31c of the first claw-shaped magnetic pole 31b and an N pole having the same polarity as the first claw-shaped magnetic pole 31b. Is magnetized so that the side in contact with the outer peripheral surface 32d becomes the S pole having the same polarity as the second core base 32a.

  Further, similarly to the first claw-shaped magnetic pole 31b, the back auxiliary magnet 35 is disposed between the back surface 32c of each second claw-shaped magnetic pole 32b and the outer peripheral surface 31d of the first core base 31a. The back auxiliary magnet 35 has a fan-shaped cross section in the direction perpendicular to the axis, and is magnetized so that the side in contact with the back surface 32c is an S pole and the side in contact with the outer peripheral surface 31d of the first core base 31a is an N pole. . As the back auxiliary magnets 34 and 35, for example, ferrite magnets can be used.

As shown in FIGS. 2 and 3, interpolar magnets 36 and 37 are disposed between the circumferential directions of the first claw-shaped magnetic pole 31b and the second claw-shaped magnetic pole 32b.
As shown in FIG. 1, the rotor 21 is separated by a separation distance B in the axial direction between the first and second rotor cores 31 and 32 and the yoke housing 13 (bottom portion 13 a). The separation distance B is set such that the radially outer side is separated from the radially inner side, and the separation distance B1 <the separation distance B2. Here, the first and second claw-shaped magnetic poles 31b and 32b (first and second rotor cores 31 and 32) are separated from the stator 16 (stator core 17) by a predetermined distance (separation distance A) in the radial direction. ing. The separation distance B / the separation distance A is set to be in a range of 5.0 ≦ B / A ≦ 9.0.

  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. The magnet fixing member 41 is fixed on the side close to the first rotor core 31 with the boss portion 41 a fitted on the rotary shaft 22.

  In the 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. When the Hall IC 43 senses the N-pole and S-pole magnetic fields based on the sensor magnet 42, it outputs an H level detection signal and an L level detection signal to the control circuit S, respectively.

Next, the operation of the brushless motor 11 configured as described above will be described.
When a three-phase driving current is supplied from the control circuit S to the winding 20, 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 20 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.

  Here, in this embodiment, when the distance in the radial direction between the stator and the claw-shaped magnetic pole is A, and the distance in the axial direction between the first and second rotor cores and the yoke housing is B, 5.0 ≦ The range is B / A ≦ 9.0. FIG. 5 shows TN characteristics (torque-rotational speed characteristics) and TI characteristics (torque-current characteristics) when B / A is changed, and FIG. 6 shows B / A at the rated load. The current ratio when changed is shown. In FIG. 5, a graph of the TI characteristic when B / A is “3” is indicated by a line Ti1, and a graph of the TI characteristic when B / A is “6” is indicated by a line Ti2. A graph of the TI characteristic when A is “9” is indicated by a line Ti3. In FIG. 5, the TN characteristic graph when B / A is “3” is indicated by a line Tn1, and the TN characteristic graph when B / A is “6” is indicated by a line Tn2. A graph of the TN characteristic when B / A is “9” is indicated by a line Tn3. In FIG. 6, the DC current with B / A of “6” is shown as 100%. As can be seen from FIG. 5, the larger the value of B / A, the higher the torque obtained with the same DC current. As can be seen from FIG. 6, when the B / A is less than “5”, the DC current is remarkably lowered, but when B / A is “5” or more, the decrease rate becomes moderate. Thus, by setting B / A to be “5” or more, the first and second rotor cores 31 and 32, the yoke housing 13 and the separation distance A in the radial direction between the stator 16 and the claw-shaped magnetic poles 31b and 32b Since the separation distance B in the axial direction is ensured and the leakage magnetic flux in the axial direction is reduced, the output characteristics (motor characteristics) are improved.

  Further, the yoke body 13 made of a magnetic material (made of iron) is positioned on one end surface side of the rotor 21 in the axial direction, and the end plate 14 made of resin is positioned on the other end surface side of the rotor 21 in the axial direction. A part of the magnetic flux from 33 may leak to the case 12 side (yoke housing 13 side) and the magnetic balance may be lost.

  That is, as shown in FIG. 7, the detent torque C1 generated by one magnetic pole and the detent torque C2 generated by the other magnetic pole satisfy C1> C2, and a peak difference CX (= C1-C2) occurs.

  Therefore, in the present embodiment, the B / A range is set to “5” or more as described above, so that the rotor cores 31 and 32 with respect to the radial distance A between the claw-shaped magnetic poles 31 b and 32 b and the stator 16. A sufficient separation distance B in the axial direction between the yoke housing 13 and the yoke housing 13 is ensured to suppress leakage magnetic flux from the yoke housing 13 side. As a result, as shown in FIG. 8, the peak difference CX is reduced and the magnetic balance can be improved. Furthermore, since both the detent torques C1 and C2 are generally improved, the holding force of the rotor 21 can be increased.

Next, the effect of this embodiment will be described.
(1) The distance in the radial direction between the stator 16 and the claw-shaped magnetic poles 31b and 32b is A, and the distance in the axial direction between the first and second rotor cores 31 and 32 and the yoke housing 13 (bottom portion 13a) is B. At this time, by setting the range to 5.0 ≦ B / A, as shown in FIGS. 5 and 6, it is possible to suppress the leakage magnetic flux and improve the output characteristics (motor characteristics). Further, as can be seen from FIG. 8, by increasing the B / A and increasing the axial distance between the rotor cores 31 and 32 and the yoke housing 13 made of a magnetic material, the leakage flux is reduced, and the detent torques C1 and C2 are reduced. Therefore, the holding force of the rotor 21 can be increased.

  (2) The distance between the rotor cores 31 and 32 and the yoke housing 13 in the axial direction is set to be longer at the radially outer side, which is a portion having a large surface area per circumference, than at the radially inner side, thereby making it possible to more appropriately prevent the leakage magnetic flux. It can be reduced.

In addition, you may change the said embodiment as follows.
In the above embodiment, the axial separation distance B (B1, B2) between the rotor cores 31, 32 and the yoke housing 13 (bottom 13a) is configured to be different between the radially inner side and the radially outer side. Not exclusively.

  For example, as shown in FIG. 9, a configuration in which the separation distance B (B1 = B2) is constant between the radially inner side and the radially outer side may be employed. Further, the configuration may be adopted so that the radially inner separation distance B1 and the radially outer separation distance B2 satisfy B1> B2.

In the above embodiment, the upper limit of B / A is “9”, but it may be more than this.
In the above embodiment, the brushless motor is embodied in which the number of poles of the rotor 21 is set to “10” and the number of teeth 17a of the stator 16 is set to “12”, but the number of poles of the rotor 21 and the stator 16 The number of teeth 17a may be changed. For example, the present invention may be embodied in a brushless motor in which 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 the above embodiment, the back auxiliary magnets 34 and 35 and the interpolar magnets 36 and 37 are provided on the rotor 21, but this is not a limitation. For example, a configuration in which only the back auxiliary magnet is provided, a configuration in which only the interpole magnet is provided, or a configuration in which the back auxiliary magnet and the interpole magnet are omitted may be employed.

  -You may combine the said each modification suitably.

  DESCRIPTION OF SYMBOLS 10 ... Motor, 12 ... Case, 13 ... Yoke housing, 14 ... End plate as a cover part, 16 ... Stator, 17 ... Stator core, 17a ... Teeth, 20 ... Winding, 21 ... Rotor, 31, 32 ... Rotor core, 31 ... 1st rotor core, 31b, 32b ... Claw-shaped magnetic pole, 32 ... 2nd rotor core, A, B, B1, B2 ... Separation distance.

Claims (2)

A stator core having a plurality of radially extending teeth in the circumferential direction, and a stator having a winding wound around the teeth;
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. The first and second rotor cores arranged alternately in the circumferential direction and the core bases are arranged between the axial directions and magnetized in the axial direction, so that the claw-shaped magnetic poles of the first rotor core are first And a field magnet that causes the claw-shaped magnetic pole of the second rotor core to function as the second magnetic pole,
A motor housed in a case having a bottomed cylindrical magnetic housing and a lid for closing the opening of the yoke housing;
The range of 5.0 ≦ B / A, where A is the radial distance between the stator and the claw-shaped magnetic pole, and B is the axial distance between the first and second rotor cores and the yoke housing. A motor characterized by The motor according to claim 1,
The motor according to claim 1, wherein a distance in the axial direction between the rotor core and the yoke housing is longer on a radially outer side than on a radially inner side.