JP2014082903A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor capable of suppressing noise generation while decreasing the number of magnets even in the case where the number of pole couples becomes odd.SOLUTION: In a brushless motor 1 comprising a stator core 2 around which a three-phase coil is wound and a rotor 5 including a plurality of magnets 10, the number of magnetic poles is 4m+2 ((m) is a natural number), and the number of slots is 3m+3 or 3m+6 and different from the number of magnetic poles. A part of magnetic poles is formed from a first magnet 11 and a second magnet 12 which are disposed one by one so as to be positioned oppositely to each other in a rotating direction of the rotor 5. The remaining magnetic poles are formed from third magnets 13 and fourth magnets 14 which are disposed so as to be positioned oppositely to each other in the rotating direction of the rotor 5. There is one magnetic pole formed from the first magnet 11 and the second magnet 12, and there are two magnetic poles formed from the third magnets 13 and the fourth magnets 14. Polarities are inverse between portions included at positions opposite to each other in the rotating direction of the rotor 5.

Description

  The present invention relates to a brushless motor, and in particular, a brushless motor including a stator having a plurality of slots formed for winding a three-phase coil and a rotor having a plurality of magnets arranged in the rotational direction. About.

  Among the brushless motors, there is an outer rotor type including a stator having a plurality of slots formed for winding a three-phase coil, and a rotor having a plurality of magnets arranged in the rotation direction. Exists (see, for example, Patent Document 1). The brushless motor disclosed in Patent Document 1 has 10 poles and 12 slots, and is configured so that the interval between teeth is alternately switched along the rotation direction of the motor for the purpose of improving motor efficiency.

JP 2010-98937 A

  By the way, in order to reduce the number of motor components, the rotor may be provided with magnets constituting a plurality of magnetic poles. For example, if magnets that constitute two magnetic poles (one N pole and one S pole) are used, the number of magnets to be prepared is halved. However, when the magnetic poles are 6 poles, 10 poles, and 14 poles, that is, when the number of pole pairs is an odd number, the arrangement pattern of the magnets inevitably forms an asymmetric magnetic flux distribution. End up.

  More specifically, when the number of pole pairs is an odd number, if magnets that form two magnetic poles are used, the number of magnets also becomes an odd number. In such a case, as shown in FIG. 5, the magnet arrangement pattern is such that the magnet exists at a position shifted by 180 degrees from the gap between the magnets. FIG. 5 is a diagram illustrating a magnet arrangement pattern in a brushless motor according to a comparative example.

And in said magnet arrangement pattern, as shown in FIG. 4, when the rotor rotates, the force which generate | occur | produces in a stator pulsates, and noise comes to increase in connection with this.
Therefore, an object of the present invention has been made in view of the above-described problems, and a brushless motor capable of suppressing noise generation while reducing the number of magnets even when the number of pole pairs is an odd number. It is to provide.

  According to the brushless motor of the present invention, the object includes a stator having a plurality of slots formed to wind a three-phase coil, and a rotor having a plurality of magnets arranged in the rotation direction. In the brushless motor, the number of the plurality of magnetic poles configured by the plurality of magnets is 4m + 2 (m is a natural number), the number of the plurality of slots is 3m + 3 or 3m + 6, and the number of the plurality of magnetic poles And a part of the plurality of magnetic poles is configured by a first magnet and a second magnet arranged one by one so as to be located at positions opposite to each other in the rotation direction, and the remaining magnetic poles Is composed of a third magnet and a fourth magnet arranged so as to be positioned opposite to each other in the rotational direction, and is composed of each of the first magnet and the second magnet. The number of magnetic poles is the same number and an odd number, and the first magnet and the second magnet are opposite in polarity to each other at positions opposite to each other in the rotation direction, and the third magnet and the fourth magnet Resolved by the fact that the number of magnetic poles constituted by each of the magnets is the same number and an even number, and the third magnet and the fourth magnet have opposite polarities between the parts that are opposite to each other in the rotation direction. Is done.

  According to the above brushless motor, since there are one first magnet and one second magnet, and there are the same number of third magnets and fourth magnets, it is possible to realize a magnet arrangement pattern in which the magnetic flux distribution is symmetric. Is possible. That is, it is possible to arrange each magnet so that a similar gap exists at a position shifted by 180 degrees from the gap between the magnets. Therefore, with the brushless motor according to the present invention, even if the number of pole pairs is an odd number, the pulsation of the force generated in the stator is further suppressed while using the magnets constituting a plurality of magnetic poles per piece, and the pulsation is accompanied. Noise can be reduced.

In the brushless motor, the length of the first magnet in the rotation direction and the length of the second magnet in the rotation direction are equal to each other, and the length of the third magnet in the rotation direction and the rotation It is preferable that the lengths of the fourth magnets in the direction are equal to each other.
If it is said structure, it will become possible to implement | achieve more effectively the magnet arrangement pattern that magnetic flux distribution becomes symmetrical.

In the above brushless motor, when m is any one of 1 to 3, there is one magnetic pole formed by each of the first magnet and the second magnet, and the third magnet and the second magnet The number of magnetic poles formed by each of the four magnets is preferably two.
With the above configuration, a brushless motor having a configuration in which the number of magnetic poles is close to the number of slots, specifically, 6 poles, 9 slots, 10 poles, 9 slots, 10 poles, 12 slots, 14 poles, 12 slots, and 14 poles, 15 slots. In the brushless motor, noise generation can be suppressed while reducing the number of magnets.

The brushless motor may be an outer rotor type brushless motor having a stator core as the stator and the rotor surrounding the stator core.
In the outer rotor type brushless motor, since the rotor is generally larger than the inner rotor type motor, the noise generated when the magnetic flux distribution becomes asymmetric is also increased. Therefore, if it is an outer rotor type brushless motor, the effect of this invention which suppresses generation | occurrence | production of a noise will be show | played more effectively.

  According to the brushless motor of the present invention, by arranging the magnets so that the magnetic flux distribution is symmetric, it is possible to suppress noise generation while reducing the number of magnets even when the number of pole pairs is an odd number. It becomes possible.

It is a figure which shows the 1st example of the magnet arrangement pattern in the brushless motor which concerns on this invention. It is a figure which shows the 2nd example of the magnet arrangement pattern in the brushless motor which concerns on this invention. It is a figure which shows the 3rd example of the magnet arrangement pattern in the brushless motor which concerns on this invention. It is a figure which shows the graph which shows the relationship between the rotation angle of a rotor, and the force which generate | occur | produces in a stator. It is a figure which shows the magnet arrangement pattern in the brushless motor which concerns on a comparative example.

Hereinafter, a specific configuration of the brushless motor of the present invention will be described with reference to FIGS.
1 to 3 are diagrams showing a magnet arrangement pattern in a brushless motor according to the present invention. FIG. 1 shows a first example of the magnet arrangement pattern. FIG. 2 shows a second example. 3 shows a third example. 1 to 3, for convenience of explanation, illustration of a three-phase coil wound around each slot is omitted.
FIG. 4 is a graph showing a relationship between the rotation angle of the rotor and the force generated in the stator. In FIG. 4, the horizontal axis indicates the rotation angle of the rotor (unit is degree), and the vertical axis indicates the unbalanced load (unit is N ). Further, in FIG. 4, a graph when the number of magnets is five is indicated by a broken line, and a graph when the number of magnets is an even number is indicated by a thick solid line.

First, an overall configuration of a brushless motor (hereinafter, this motor) 1 according to the present invention will be outlined. The motor 1 is an outer rotor type brushless motor, and is used as an electric motor for a blower or a fan.
The configuration of the motor 1 is the same as that of a conventional outer rotor type brushless motor. More specifically, as shown in FIG. 1, the motor 1 has a stator core 2 as a stator and a rotor 5 surrounding the stator core 2. The stator core 2 has a plurality of substantially T-shaped teeth 3 extending radially from the annular portion 2a at regular intervals. A slot 4 is formed between the teeth 3 so as to wind a three-phase coil (not shown). In the motor 1, each of the three-phase coils is wound around the corresponding tooth 3 by concentrated winding.

  The rotor 5 has a cylindrical rotor core 6 and a plurality of magnets 10 attached to the inner peripheral surface of the rotor core 6, and rotates with the rotation of a shaft (not shown). The plurality of magnets 10 constitute a field body in the motor 1 and generate a field magnetic flux in a state of being aligned along the rotation direction of the rotor 5 (hereinafter simply referred to as the rotation direction). More specifically, each of the plurality of magnets 10 constitutes a magnetic pole, and each magnet 10 is arranged so that the magnetic poles are alternately switched along the rotation direction.

The plurality of magnets 10 constitute a plurality of magnetic poles. In particular, in the motor 1, the number of magnetic poles (the number of magnetic poles) formed by the plurality of magnets 10 is 4m + 2 (m is a natural number). In other words, the number of pole pairs in the motor 1 is 2m + 1, that is, an odd number.
Hereinafter, a case where m = 2, that is, a case where the number of magnetic poles is 10 will be described as an example. However, the present invention is not limited to this, and m may be any one of 1 to 3, that is, the number of magnetic poles may be any one of 6, 10, and 14.

  Further, in the motor 1, among the plurality of magnets 10, there is a magnet 10 (specifically, a third magnet 13 and a fourth magnet 14 described later) that form a plurality of magnetic poles. When a plurality of magnetic poles are magnetized on one magnet 10 as described above, the number of magnets 10 to be prepared can be reduced with respect to a predetermined number of magnetic poles, so that the number of motor components is reduced. The cost required for processing and mounting of the magnet 10 is reduced.

  On the other hand, the number of slots 4 formed in the stator core 2 is a number close to the number of magnetic poles, specifically 3m + 3 or 3m + 6, and the number of magnetic poles (a plurality of magnetic poles composed of a plurality of magnets 10). The number of magnetic poles). Hereinafter, a case where the number of slots 4 (hereinafter, the number of slots) is 12 will be described as an example. That is, the following description relates to a configuration example of an outer rotor type brushless motor having 10 poles and 12 slots.

Next, the characteristic configuration and superiority of the motor 1 will be described.
In describing the characteristic configuration of the motor 1, the configuration of the brushless motor according to the comparative example will be described. A brushless motor (hereinafter referred to as a comparative motor) 21 according to a comparative example is an outer rotor type brushless motor, similar to the motor 1, and its internal structure is as shown in FIG.
More specifically, the comparison motor 21 has a configuration of 10 poles and 12 slots, and includes a plurality of magnets 30 arranged in the rotational direction as field bodies. As shown in FIG. 5, in the comparison motor 21, each of the plurality of magnets 30 constitutes two magnetic poles. That is, the number of magnets 30 provided in the comparison motor 21 is five. Further, in the comparison motor 21, the length of each magnet 30 in the rotation direction (the length indicated by the symbol d in FIG. 5 and hereinafter referred to as the circumferential length) is substantially uniform, Magnets 30 are arranged at substantially equal intervals.

  In the comparison motor 21 configured as described above, the odd number of magnets 30 are arranged at equal intervals along the rotation direction, and the magnets 30 are present at positions shifted by 180 degrees from the gaps between the magnets 30. In such a magnet arrangement pattern, as described above, the magnetic flux distribution in the rotor 25 is asymmetric in the rotational direction. And in asymmetrical magnetic flux distribution, the force which generate | occur | produces in the stator core 22 during the rotation period of the rotor 5, specifically, the force which acts toward the radial direction outer side of the rotor 25 pulsates. Thus, when the force generated in the stator core 22 is unbalanced, noise generated with the rotation of the rotor 25 increases. In particular, in the outer rotor type brushless motor, the rotor diameter is larger than that in the inner rotor type, so that the noise generated when the magnetic flux distribution becomes asymmetrical becomes larger.

In contrast, the motor 1 employs a configuration that suppresses the pulsation of the force generated in the stator core 2. Thereby, in this motor 1, it becomes possible to reduce the noise which arises with rotation of the rotor 5. FIG. Hereinafter, the above configuration employed by the motor 1 will be described in detail.
As described above, the motor 1 is provided with a plurality of magnets 10 constituting a field body. Among the plurality of magnets 10, there are magnets 10 having different numbers of magnetic poles. Exists. More specifically, the plurality of magnets 10 includes a first magnet 11 and a second magnet 12 that are magnets 10 constituting an odd number of magnetic poles, and a third magnet 13 that is a magnet 10 constituting an even number of magnetic poles. And a fourth magnet 14. In other words, some of the plurality of magnetic poles (more specifically, 10 poles) formed by the plurality of magnets 10 are configured by the first magnet 11 and the second magnet 12, and the remaining magnetic poles are the third. The magnet 13 and the fourth magnet 14 are configured.

Here, as shown in FIG. 1, the first magnet 11 and the second magnet 12 are arranged one by one so as to be located at positions opposite to each other (that is, positions shifted by 180 degrees) in the rotation direction. Further, the number of magnetic poles constituted by each of the first magnet 11 and the second magnet 12 is the same number and an odd number. Furthermore, the magnetic poles have opposite polarities between the portions that the first magnet 11 and the second magnet 12 have at opposite positions in the rotation direction.
More specifically, in the motor 1, there is one magnetic pole formed by each of the first magnet 11 and the second magnet 12, and the magnetic pole formed by the first magnet 11 (N in the case shown in FIG. 1). Pole) and the magnetic pole (the S pole in the case shown in FIG. 1) formed by the second magnet 12 have opposite polarities.

On the other hand, as shown in FIG. 1, the same number of third magnets 13 and fourth magnets 14 are arranged so as to be located at positions opposite to each other in the rotation direction (that is, positions shifted by 180 degrees). Further, the number of magnetic poles constituted by each of the third magnet 13 and the fourth magnet 14 is the same and an even number. Furthermore, the magnetic poles have opposite polarities between the portions that the third magnet 13 and the fourth magnet 14 have at opposite positions in the rotational direction.
Specifically, in the motor 1, each of the third magnet 13 and the fourth magnet 14 constitutes two magnetic poles, and two pieces are provided between the first magnet 11 and the second magnet 12 in the rotation direction. It is arranged one by one. In the third magnet 13, there is a portion constituting the S pole (N pole) in the fourth magnet 14 at a position shifted by 180 degrees from the portion constituting the N pole (S pole).

  In the motor 1, the circumference of the first magnet 11 (denoted as symbol d1 in FIG. 1 and the like) and the circumference of the second magnet 12 (denoted as symbol d2 in FIG. 1 and the like) are equal to each other. Further, the circumference of the third magnet 13 (denoted as symbol d3 in FIG. 1 and the like) and the circumference of the fourth magnet 14 (denoted as symbol d4 in FIG. 1 and the like) are equal to each other. Further, in the motor 1, the circumferences of the first magnet 11, the second magnet 12, the third magnet 13, and the fourth magnet 14 are lengths corresponding to the number of magnetic poles constituting the motor 1. More specifically, the circumference of each of the third magnet 13 and the fourth magnet 14 is about twice the circumference of the first magnet 11 or the second magnet 12.

  The first magnet 11, the second magnet 12, the third magnet 13 and the fourth magnet 14 described so far are arranged as shown in FIG. A symmetrical magnet arrangement pattern is realized. That is, in the present motor 1, since the plurality of magnets 10 are configured by the set of the first magnet 11 and the second magnet 12, and the set of the third magnet 13 and the fourth magnet 14, the number of the magnets 10 is an even number (specifically 6). Furthermore, the circumference of each of the first magnet 11, the second magnet 12, the third magnet 13, and the fourth magnet 14 is a length corresponding to the number of magnetic poles constituting the first magnet 11, the second magnet 12, the third magnet 13, and the fourth magnet 14. Thereby, the magnets 10 can be arranged so that the arrangement of the magnetic poles is point-symmetric with respect to the rotation center of the rotor 5. That is, a similar gap exists at a position shifted by 180 degrees from the gap between the magnets 10.

  Since the above magnetic arrangement pattern, that is, the magnet arrangement pattern shown in FIG. 1, makes the magnetic flux distribution symmetrical, as shown in FIG. 4, the pulsation of the force acting on the stator core 2 during the rotation period of the rotor 5 is improved. It becomes possible to suppress. Accordingly, in the motor 1, even if the number of pole pairs is an odd number, it is possible to reduce noise generated with the rotation of the rotor 5 while forming a plurality of magnetic poles in one magnet 10. The above effects are particularly effective in an outer rotor type brushless motor. That is, as described above, in the outer rotor type brushless motor, the rotor 5 is larger than the inner rotor type motor, and the noise generated when the magnetic flux distribution is asymmetrical becomes larger. Thus, the effect of suppressing the noise by arranging the magnet 10 becomes more significant.

  Note that the magnet arrangement pattern in which the magnetic flux distribution is symmetric is not limited to that shown in FIG. 1 (hereinafter referred to as the first example), and other magnet arrangement patterns are also conceivable. Below, the example (henceforth the 2nd example) illustrated in Drawing 2 and the example (henceforth the 3rd example) illustrated in Drawing 3 as a modification of a magnet arrangement pattern are explained.

First, a brushless motor (hereinafter referred to as a second example motor) 101 according to a second example will be described.
The motor 101 of the second example is an outer rotor type brushless motor, like the motor 1, and has 10 poles and 12 slots. Also in the motor 101 of the second example, the plurality of magnets 110 includes the first magnet 111 and the second magnet 112 that form an odd number of magnetic poles, and the third magnet 113 that is the magnet 110 that forms an even number of magnetic poles. It consists of a fourth magnet 114.
And in the 2nd example, as shown in Drawing 2, the number of the magnetic poles which the 1st magnet 111 and the 2nd magnet 112 constitute is 3, and each of the 1st magnet 111 and the 2nd magnet 112 One by one is arranged so as to be opposite to each other in the rotational direction. In the second example, each of the third magnet 113 and the fourth magnet 114 is disposed between the first magnet 111 and the second magnet 112 in the rotation direction.

In the second example, the circumference of each of the first magnet 111 and the second magnet 112 is about 1.5 times the circumference of the third magnet 113 or the fourth magnet 114.
The motor 101 of the second example is different from the motor according to the first example, that is, the motor 1 in the above points, but has the same configuration as the motor 1 in other points.
In the second example, the number of magnets 110 is four, and the circumference of each magnet 110 is a length corresponding to the number of magnetic poles, so that the arrangement of the magnetic poles is point-symmetric with respect to the rotation center of the rotor 105. Thus, each magnet 110 can be arranged. As a result, also in the second example, since the magnetic flux distribution is symmetric, it is possible to satisfactorily suppress the pulsation of the force acting on the stator core 102 during the rotation period of the rotor 105, and thus during the rotation of the rotor 105. It is possible to suppress noise generated in the case.

Next, a brushless motor (hereinafter referred to as a third example motor) 201 according to a third example will be described.
The motor 201 of the third example is also an outer rotor type brushless motor and has 10 poles and 12 slots. The motor 201 of the third example includes a first magnet 211 and a second magnet 212 that constitute a single magnetic pole, and a third magnet 213 and a fourth magnet 214 that are magnets 210 that constitute four magnetic poles. .
In the third example, as shown in FIG. 3, the first magnet 211 and the second magnet 212 are arranged one by one so as to be positioned opposite to each other in the rotation direction, and the third magnet 213 and Each of the fourth magnets 214 is disposed between the first magnet 211 and the second magnet 212 in the rotational direction. In the third example, the circumference of each of the third magnet 213 and the fourth magnet 214 is about four times the circumference of the first magnet 211 or the second magnet 212.
In the above points, the motor 201 of the third example is different from the motor 1 as the motor according to the first example, but has the same configuration as the motor 1 in other points.

  In the third example, the number of magnets 210 is four, and the circumference of each magnet 210 is a length corresponding to the number of magnetic poles. Therefore, the arrangement of the magnetic poles is point-symmetric with respect to the rotation center of the rotor 205. Thus, each magnet 210 can be arranged. As a result, also in the third example, since the magnetic flux distribution is symmetric, it is possible to satisfactorily suppress the pulsation of the force acting on the stator core 202 during the rotation period of the rotor 205, and thus, during the rotation of the rotor 205. It is possible to suppress noise generated in the case.

  The configuration example of the brushless motor according to the embodiment of the present invention has been described above. However, the above configuration example is for facilitating the understanding of the present invention, and does not limit the present invention. . The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

In the above embodiment, the brushless motor having 10 poles and 12 slots has been described as an example. However, the number of poles and the number of slots are 6 poles, 9 slots, 10 poles, 8 slots, 14 poles, 12 slots, 14 It may be any of the pole 15 slots.
In the above embodiment, the outer rotor type brushless motor has been described as an example. However, the present invention can also be applied to an inner rotor type brushless motor.
In the above embodiment, the interval (pitch) between the teeth 3 in the rotation direction is constant, but the pitch may be switched alternately.

1 motor, 101 second example motor, 201 third example motor 2, 102, 202 stator core 2a annular portion, 3 teeth, 4 slots 5, 105, 205 rotor 6 rotor core 10, 110, 210 magnet 11, 111 , 211 First magnet 12, 112, 212 Second magnet 13, 113, 213 Third magnet 14, 114, 214 Fourth magnet 21 Comparison motor 22 Stator core, 25 Rotor 30 Magnet

Claims (4)

A brushless motor comprising: a stator having a plurality of slots formed for winding a three-phase coil; and a rotor having a plurality of magnets arranged in the rotational direction,
The number of magnetic poles constituted by the plurality of magnets is 4m + 2 (m is a natural number),
The number of the plurality of slots is 3m + 3 or 3m + 6, and is different from the number of the plurality of magnetic poles;
A part of the plurality of magnetic poles is composed of a first magnet and a second magnet arranged one by one so as to be positioned opposite to each other in the rotation direction, and the remaining magnetic poles are in the rotation direction. The third magnet and the fourth magnet disposed so as to be opposite to each other,
The number of magnetic poles constituted by each of the first magnet and the second magnet is the same number and an odd number, and between the portions of the first magnet and the second magnet that are opposite to each other in the rotation direction. With reverse polarity,
The number of magnetic poles formed by each of the third magnet and the fourth magnet is the same number and an even number, and between the portions that the third magnet and the fourth magnet have at opposite positions in the rotation direction. A brushless motor characterized by having a reverse polarity. The length of the first magnet in the rotational direction and the length of the second magnet in the rotational direction are equal to each other;
2. The brushless motor according to claim 1, wherein a length of the third magnet in the rotation direction is equal to a length of the fourth magnet in the rotation direction. When m is any one of 1 to 3,
The number of magnetic poles formed by each of the first magnet and the second magnet is one,
The brushless motor according to claim 2, wherein the number of magnetic poles formed by each of the third magnet and the fourth magnet is two.   The brushless motor according to any one of claims 1 to 3, wherein the brushless motor is an outer rotor type brushless motor having a stator core as the stator and the rotor surrounding the stator core.

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