JP5996443B2 - Brushless motor - Google Patents

Description

  The present invention relates to 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.

Japanese Utility Model Publication No. 5-43749

  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, the brushless motor requires a sensor magnet, which increases the number of parts and further increases the number of assembly steps. In addition, the rotor as described above is configured to use a magnetic flux that is magnetized in the axial direction by the field magnet and includes axial magnetic flux (including leakage magnetic flux that extends in the axial direction outside the rotor). If a sensor magnet is provided, there is a concern about the influence of the sensor magnet on the motor characteristics. This is a cause of requiring a rotor design that also considers sensor magnets, for example.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a brushless motor that can reduce the number of parts and avoid the influence of the sensor magnet on the motor characteristics. It is to provide.

A brushless motor that solves the above-described problems is formed by a plurality of claw-shaped magnetic poles protruding radially outward at equal intervals on the outer periphery of a substantially disk-shaped core base, and extending in the axial direction. The first and second rotor cores in which the claw-shaped magnetic poles are alternately arranged in the circumferential direction while the bases are opposed to each other are arranged between the axial directions of the core bases, and are magnetized in the axial direction. A rotor having a field magnet that causes the claw-shaped magnetic pole of the rotor core to function as a first magnetic pole and the claw-shaped magnetic pole of the second rotor core to function as a second magnetic pole, and opposed to a radially outer side of the rotor. The brushless motor includes a stator that generates a rotating magnetic field, and a magnetic sensor that is fixed with respect to the stator and detects a rotational position of the rotor. A position facing the axially are arranged in matched positions with the claw-shaped magnetic poles in the radial direction, the opposing surfaces of the magnetic sensor of the claw-shaped magnetic poles is provided protrusion protruding axially is, the convex portion, Ru is formed to a position of the first and second radial portion extending in the axial direction of each of the claw-shaped magnetic poles of the rotor core.

  According to this configuration, since the magnetic sensor is disposed at a position facing the axial direction of the rotor and in a position that coincides with the claw-shaped magnetic pole in the radial direction, the rotational position of the rotor is not particularly required without using a sensor magnet. Can be detected. In other words, in the above configuration, when the rotor rotates, the magnetic sensor has a magnetic sensor position that matches the circumferential position of the claw-shaped magnetic pole of the first rotor core and the circumferential position of the claw-shaped magnetic pole of the second rotor core. The direction of the leakage magnetic flux passing through can be made different. Therefore, the rotational position of the rotor can be detected by the magnetic sensor without using a sensor magnet. In addition, the influence of the sensor magnet on the motor characteristics can be avoided, and for example, the rotor can be easily designed.

According to this configuration, since the convex portion protruding in the axial direction is provided on the surface of the claw-shaped magnetic pole facing the magnetic sensor, the circumferential position of the portion (convex portion) matches the magnetic sensor. The direction of the leakage magnetic flux passing through the magnetic sensor can be made remarkable, and the rotational position of the rotor can be detected more accurately and stably.
In addition, since the convex portions are formed at radial positions of the portions extending in the axial direction in the claw-shaped magnetic poles of the first and second rotor cores, the leakage magnetic flux that passes through the magnetic sensor by the respective convex portions. The orientation can be made remarkable, and the rotational position of the rotor can be detected more accurately and stably.

In the brushless motor, the convex portion is preferably formed integrally with the claw-shaped magnetic pole.
According to this configuration, since the convex portion is integrally formed with the claw-shaped magnetic pole, for example, the number of parts and the number of assembling steps can be suppressed as compared with the case where the convex portion is fixed separately. In addition, for example, if the convex part is fixed separately, the flow of magnetic flux may become unstable depending on the assembly accuracy, but the flow of magnetic flux is stable compared to this, and the rotational position of the rotor is more It becomes possible to detect accurately and stably.

  In the brushless motor, it is preferable that the heights of the convex portions of the first rotor core and the convex portions of the second rotor core are made different so as to approach each other so that the magnetic flux density in the magnetic sensor is switched evenly.

According to this configuration, since the height of the convex portion of the first rotor core and the convex portion of the second rotor core are different so that the magnetic flux density in the magnetic sensor is switched evenly, the detection signal of the magnetic sensor Based on this, it becomes possible to supply the drive current to the stator at a more optimal timing.
The brushless motor includes a back auxiliary magnet provided radially inside the claw-shaped magnetic pole and magnetized in the radial direction.
The brushless motor includes an interpole magnet magnetized in the circumferential direction between the claw-shaped magnetic poles adjacent to each other in the circumferential direction.

  In the brushless motor of the present invention, the number of parts can be reduced, and the influence of the sensor magnet on the motor characteristics can be avoided.

Sectional drawing of the brushless motor in one Embodiment. The partial cross section perspective view of the brushless motor in the same form. (A) is a schematic diagram explaining the magnetic flux when the circumferential direction position of a 1st claw-shaped magnetic pole corresponds with respect to Hall IC. (B) is a schematic diagram explaining the magnetic flux when the circumferential direction position of a 2nd claw-shaped magnetic pole corresponds with respect to Hall IC. Rotation angle-magnetic flux density characteristic diagram. The perspective view of the rotor in another example. The perspective view of the rotor in another example. The perspective view of the rotor in another example. The perspective view of the rotor in another example. Rotation angle-magnetic flux density schematic characteristic diagram.

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.

  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”.

Further, the rotor 21 of the present embodiment includes a back auxiliary magnet 34 that is provided on the radially inner side (back surface) of the first and second claw-shaped magnetic poles 31b and 32b and is magnetized in the radial direction.
As shown in FIG. 1, in the front end plate 14, the substrate is located at a position facing the axial direction of the rotor 21 and in a radial direction with the first and second claw-shaped magnetic poles 31 b and 32 b. Hall IC 42 as a magnetic sensor mounted on 41 is disposed. Specifically, the Hall IC 42 of the present embodiment is disposed at a position facing a portion projecting radially outward of the first claw-shaped magnetic pole 31b in the first rotor core 31, and more specifically, a portion projecting radially outward. Are arranged with a gap of 2 mm in the axial direction and the center position in the radial direction. The Hall IC 42 outputs an H level detection signal and an L level detection signal to the control circuit S in accordance with the direction of the magnetic flux passing through the Hall IC 42 (leakage magnetic flux from the rotor 21).

Next, the operation of the brushless motor 11 configured as described above will be described.
For example, as shown in FIG. 3A, when the circumferential position of the first claw-shaped magnetic pole 31b of the first rotor core 31 coincides with the Hall IC 42 when the rotor 21 rotates, the first claw-shaped magnetic pole Leakage magnetic flux from the end face in the axial direction of 31b toward the outside in the axial direction (in the figure, the leakage magnetic flux directed upward, see arrow A) passes through the Hall IC 42.

  For example, as shown in FIG. 3B, when the circumferential position of the second claw-shaped magnetic pole 32b of the second rotor core 32 coincides with the Hall IC 42, the axial end surface of the first core base 31a. Leakage magnetic flux toward the axial end surface of the second claw-shaped magnetic pole 32b after going from the outside in the axial direction (refer to arrow B in the figure, the downward leakage flux) passes through the Hall IC 42.

  Here, FIG. 4 shows the characteristic X as a result of measuring the magnetic flux density at the position of the Hall IC 42 of the present embodiment, and it can be seen that the magnetic pole (direction of leakage magnetic flux) is switched approximately every 45 °. The characteristic Y is a result of measuring the magnetic flux density at the radial position facing the first core base 31a. In this case, it can be seen that the magnetic pole (direction of leakage magnetic flux) is not switched.

  Thereby, in the present embodiment, the level of the detection signal output from the Hall IC 42 is switched according to the rotation angle (position) of the rotor 21, and the optimal timing from the control circuit S to the winding 19 based on the detection signal. A three-phase driving current to be switched is supplied to generate a rotating magnetic field, and the rotor 21 is driven to rotate continuously and satisfactorily.

Next, the characteristic effects of the above embodiment will be described below.
(1) The Hall IC 42 is disposed at a position facing the rotor 21 in the axial direction and in a position that coincides with the first and second claw-shaped magnetic poles 31b and 32b in the radial direction, so that a sensor magnet is not particularly used. The rotational position of the rotor 21 can be detected. That is, in the above configuration, when the rotor 21 rotates, the Hall IC 42 is moved when the circumferential position of the first claw-shaped magnetic pole 31b coincides with the Hall IC 42 and when the circumferential position of the second claw-shaped magnetic pole 32b coincides. The direction of the leakage magnetic flux passing therethrough can be varied. Therefore, the rotational position of the rotor 21 can be detected by the Hall IC 42 without using a sensor magnet. Further, the influence of the sensor magnet on the motor characteristics can be avoided, and for example, the design of the rotor 21 is facilitated.

The above embodiment may be modified as follows.
-You may provide a convex part in the opposing surface with Hall IC42 of the 1st claw-like magnetic pole 31b of the above-mentioned embodiment.

  For example, as shown in FIG. The convex portion 51 in this example is integrally formed with the first claw-shaped magnetic pole 31b (first rotor core 31). In addition, the convex part 51 of this example is shape | molded by the drawing process which moves a pressure by applying pressure from the non-opposing surface side with respect to Hall IC42 of the 1st nail | claw-shaped magnetic pole 31b.

  Further, the convex portion 51 of this example is a radial position facing the Hall IC 42, and more specifically, a radial central position at a portion projecting radially outward of the first and second claw-shaped magnetic poles 31b and 32b. Is formed. Moreover, the convex part 51 of this example is formed in the circular arc shape from the one end part of the circumferential direction of the 1st nail | claw-shaped magnetic pole 31b to the other end part.

  In this way, when the convex portion 51 is provided, the direction of the leakage magnetic flux passing through the Hall IC 42 when the circumferential position of the portion (the convex portion 51) matches the Hall IC 42 can be made remarkable. It becomes possible to detect the rotational position of the rotor 21 more accurately and stably.

  Moreover, since the convex part 51 is integrally molded with the 1st nail | claw-shaped magnetic pole 31b, compared with what the convex part is fixed separately, for example, a number of parts and an assembly man-hour can be suppressed. Further, for example, in the case where the convex portion is fixed separately, the flow of magnetic flux may become unstable depending on the assembling accuracy. However, in comparison with this, the flow of magnetic flux is stabilized and the rotational position of the rotor 21 is changed. It becomes possible to detect more accurately and stably.

  Further, since the convex portion 51 is formed in an arc shape from one end portion to the other end portion in the circumferential direction of the first claw-shaped magnetic pole 31b at the radial position facing the Hall IC 42, the circumference of the first claw-shaped magnetic pole 31b is formed. In the range in which the directional position matches the Hall IC 42, the direction of the leakage magnetic flux that always passes through the Hall IC 42 can be made remarkable.

  For example, as shown in FIG. The convex portion 52 in this example is fixed to the first claw-shaped magnetic pole 31b (for example, with an adhesive or the like). Further, the convex portion 52 of this example has a cylindrical shape, and one end thereof is fixed to the center position in the circumferential direction of the first claw-shaped magnetic pole 31b.

  Even if the convex portion 52 is provided in this manner, the direction of the leakage magnetic flux passing through the Hall IC 42 when the circumferential position of the portion (the convex portion 52) matches the Hall IC 42 can be remarkably increased. Thus, the rotational position 21 can be detected with higher accuracy and stability.

  Moreover, since the convex part 52 is being fixed to the 1st nail | claw-shaped magnetic pole 31b, the 1st and 2nd rotor cores 31 and 32 can be made into a common component, for example. Therefore, for example, the number of common parts is increased as compared with one in which a convex portion is integrally formed with one of the first claw-shaped magnetic poles 31b of the first and second rotor cores 31 and 32 (see another example (see FIG. 5)). Is possible. However, the first and second rotor cores 31 and 32 may be used as a common part by integrally forming the convex portion 51 on the second claw-shaped magnetic pole 32b of the second rotor core 32 in the above-described another example (see FIG. 5).

  For example, as shown in FIG. The convex portions 53 and 54 in this example are formed at radial positions of portions extending in the axial direction in the first and second claw-shaped magnetic poles 31b and 32b. That is, the convex portion 53 is provided on the opposite side of the axially extending side at the radial position of the portion extending in the axial direction of the first claw-shaped magnetic pole 31b. Further, the convex portion 54 is further provided so as to extend further from the tip extending in the axial direction at the radial position of the portion extending in the axial direction of the second claw-shaped magnetic pole 32b. In this example, the protruding amount of the convex portions 53, 54, that is, the height is constant. Of course, the Hall IC 42 in this example is disposed at a position that coincides with the convex portions 53 and 54 in the radial direction and that faces the convex portions 53 and 54.

  In this way, the direction of the leakage magnetic flux passing through the Hall IC 42 can be made noticeable by the respective convex portions 53 and 54, and the rotational position of the rotor 21 can be detected more accurately and stably.

  Further, for example, as shown in FIG. The convex portions 53 and 55 of this example are not constant in height as the convex portions 53 and 54 of the above-described another example (see FIG. 7), and are so high that the magnetic flux density in the Hall IC 42 is switched evenly. Are different. More specifically, in this example, the projecting portion 55 of the second claw-shaped magnetic pole 32b that functions as the S pole is located on the side that does not face the Hall IC 42 and protrudes radially outward, and the first claw-shaped magnetic pole that functions as the N pole It is formed higher than the convex part 53 of 31b.

  In this way, as indicated by the schematic characteristic Z1 in FIG. 9, the magnetic flux density at the position of the Hall IC 42 switches the magnetic pole (the direction of the leakage magnetic flux) approximately every 45 °, and the amplitude can also be made substantially equal. . The schematic characteristic Z2 in FIG. 9 is that of the above-described another example (see FIG. 7) having the convex portions 53 and 54 having a constant height. That is, when the magnetic flux density in the Hall IC 42 does not switch evenly in the convex portions 53 and 54 having a constant height as shown in FIG. 7 as shown in the schematic characteristic Z2, as shown in FIG. By making the height of 55 different, the magnetic flux density in the Hall IC 42 can be made to be switched evenly (with equal amplitude at equal angular intervals). Therefore, it becomes possible to supply a drive current to the winding 19 of the stator 16 at a more optimal timing based on the detection signal of the Hall IC 42.

  In the above embodiment, although not particularly mentioned, the first and second rotor cores 31 and 32 may be formed by forging, pressing or the like, or formed by laminating a plurality of core sheets in the axial direction. May be. Also, the convex portions 53 to 55 may be integrally formed by forging, pressing, or the like, or may be formed by laminating a plurality of core sheets for convex portions in the axial direction.

  In the above embodiment, the Hall IC 42 is disposed with a gap of 2 mm in the axial direction and the center position in the radial direction of the portion of the first rotor core 31 that protrudes radially outward of the first claw-shaped magnetic pole 31b. However, the position may be changed as long as the position is opposite to the axial direction of the rotor 21 and coincides with the first and second claw-shaped magnetic poles 31b and 32b in the radial direction. For example, the first and second claw-shaped magnetic poles 31b and 32b may be disposed at positions that coincide with the portions extending in the axial direction in the radial direction. Further, for example, the first claw-shaped magnetic pole 31b may be arranged with a gap of 1 mm in the axial direction, or may be arranged with a gap of 3 mm.

  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.

-The rotor 21 of the said embodiment is good also as what was provided with the interpolar magnet magnetized in the circumferential direction between each of the circumferential direction of 1st and 2nd claw-shaped magnetic poles 31b and 32b.
The technical idea that can be grasped from the above embodiment will be described below.

(B) pre-Kitotsu section, characterized by comprising fixed to the claw-shaped magnetic poles.
According to this configuration, since the convex portion is fixed to the claw-shaped magnetic pole, for example, the first and second rotor cores can be used as a common component. Therefore, for example, it is possible to increase the number of common parts as compared with a case in which a convex portion is integrally formed with one claw-shaped magnetic pole of the first and second rotor cores.

(B) pre-Kitotsu section, characterized in that it is formed in an arc shape to the other end portion from the circumferential end portion of the claw-shaped magnetic poles at the radial position opposite to the magnetic sensor.

  According to the same configuration, the convex portion is formed in an arc shape from one end portion to the other end portion in the circumferential direction of the claw-shaped magnetic pole at the radial position facing the magnetic sensor. In the range where the position coincides with the magnetic sensor, the direction of leakage magnetic flux that always passes through the magnetic sensor can be made remarkable.

  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 ... Hall IC (magnetic sensor), 51-55 ... projection.

Claims (5)

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 a second magnetic pole;
A stator that is arranged opposite to the radially outer side of the rotor and generates a rotating magnetic field;
A brushless motor comprising a magnetic sensor fixed to the stator and detecting a rotational position of the rotor,
The magnetic sensor is arranged at a position facing the axial direction of the rotor and in a radial direction with the claw-shaped magnetic pole ,
On the surface of the claw-shaped magnetic pole facing the magnetic sensor, a convex portion protruding in the axial direction is provided,
The brushless motor , wherein the convex portion is formed at a radial position of a portion extending in the axial direction of the claw-shaped magnetic pole of each of the first and second rotor cores. The brushless motor according to claim 1 ,
The brushless motor, wherein the convex portion is integrally formed with the claw-shaped magnetic pole. The brushless motor according to claim 1 or 2 ,
The brushless motor characterized in that the height of the convex portion of the first rotor core and the convex portion of the second rotor core are made different so as to approach each other so that the magnetic flux density in the magnetic sensor is switched evenly. The brushless motor according to any one of claims 1 to 3,
A brushless motor comprising a back auxiliary magnet which is provided radially inside the claw-shaped magnetic pole and is magnetized in the radial direction. In the brushless motor according to any one of claims 1 to 4,
A brushless motor comprising an interpole magnet magnetized in the circumferential direction between the claw-shaped magnetic poles adjacent to each other in the circumferential direction.