JP2690743B2 - Multi-pole brushless motor - Google Patents

Description

The present invention relates to a multi-pole brushless motor suitable for office automation (OA) equipment such as a personal computer and a word processor.

[Conventional technology]

A conventional brushless motor has, for example, FIGS.
It has a structure as shown in the figure.

FIG. 9 shows a brushless motor using an outer rotor, in which a rotating shaft 42 is mounted on a stator frame 40 via a bearing 41.
And a stator core 44 around which a multi-phase excitation coil 43 is wound. A rotor 45 is fixed to the rotating shaft 42, a multi-pole magnetized magnet 46 is mounted on the inner peripheral surface of the rotor 45, and a sensor 47 for detecting the speed or the position of the rotor is provided at an opposing position below the magnet 46. Is provided.

FIG. 10 shows a brushless motor using an inner rotor, and a motor case 48 supports a rotating shaft 50 via a bearing 49 and includes a stator core 52 around which a multi-phase exciting coil 51 is wound. A magnet rotor 53 whose outer peripheral surface is magnetized in multiple poles is mounted on the rotary shaft 50, and a sensor 54 for detecting the speed or position of the magnet rotor is provided at a position facing the end of the magnet rotor 53.

In such a conventional brushless motor, for example, a Hall element is used to detect the position of the magnetic pole of the rotor in order to control energization, and an optical or magnetic encoder is used to detect the speed of the rotor.

Further, when considering the structure of the stator, conventional brushless motors are roughly classified into a slot type and a slotless type.

The slot type stator is incorporated in, for example, an outer rotor type brushless motor as shown in FIG. 9, and as shown in FIG. 11, a core material in which a slot portion 55 is provided in a plate material such as a silicon steel plate. Are laminated to form a laminated core 56, and an exciting coil 57 is directly wound around the laminated core 56. Therefore, bobbins or self-bonding wires (bond wires)
Does not need However, because of the salient pole structure, there is a problem that cogging torque accompanies the torque unevenness and deteriorates the rotation unevenness characteristic.

On the other hand, in the slotless type stator, as shown in FIG. 12, ring-shaped field cores are stacked to form a ring-shaped laminated core 58, and an exciting coil 59 is provided inside or outside the ring-shaped laminated core 58.
Is formed using a bobbin or a self-bonding wire (bond wire). This slotless stator is, for example, the 10th
It is incorporated in an inner roller type brushless motor as shown in the figure. In this case, the exciting coil 59 is provided inside the ring-shaped laminated core (stator core) 58, and the magnet rotor 60 is further provided inside the coil so that the magnet rotor 60 rotates about the rotating shaft 61. ing. Therefore, the magnet rotor 60 receives a uniform magnetic attraction force at any position, so that the torque unevenness due to the cogging torque and the uneven rotation characteristic are not deteriorated.

[Problems to be solved by the invention]

Such a conventional brushless motor has the following problems.

When energization switching is performed by the hall element, the positions of the hall element and the stator are uniquely determined, and the energization method of the motor is fixed. For example, when the so-called 180 ° energization control is performed and when the 90 ° energization control is performed, the position of the Hall element is electrically different by 45 ° with respect to the magnetic pole of the stator. Therefore, one motor has two energization controls. In order to perform the above, the number of Hall elements must be doubled and arranged at positions suitable for respective energization control.

Therefore, in view of the above points, an object of the present invention is to provide a multi-pole blancless motor capable of easily switching between 180 ° energization control and 90 ° energization control.

[Means for solving the problem]

In order to achieve the above object, a multi-pole brushless motor according to the present invention has a rotor having magnetic poles on a peripheral surface at a predetermined pitch, and a comb tooth-shaped portion at the predetermined pitch and the rotor. 1st and 2nd stator sets which are mutually displaced by 1/4 pitch, coils for exciting said 1st and 2nd stator sets, and said rotor for controlling energization to said coils. A first and a second Hall element that are arranged to face the magnetic pole surface, and a first Hall element that can adjust the relative position of the first and the second Hall element.
And a second Hall element positioning member, and 180 degree energization control and 90 degree energization control are switched by adjusting the relative positions of the first and second Hall element positioning members. .

[Action]

With this configuration, the permanent magnet type stepping motor can be made into a multi-pole brushless motor. That is,
According to the present invention, the Hall element for controlling the energization of the exciting coil is arranged so as to be movable relative to each of the first and second stator sets (that is, the magnetic poles of the stator). In contrast, the electrical phase of the Hall element is arranged so that it can be adjusted), and 180 ° energization control and 90 ° energization control can be switched.

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

1 to 7 show a multi-pole brushless DC motor which is a first embodiment of the present invention.

1 to 3, reference numeral 1 denotes the entire multi-pole brushless motor according to this embodiment. This motor 1 has a stator 4 having a structure in which two stator sets 2 and 3 each having a magnetic hollow ring are vertically stacked. The surface of the stator sets 2 and 3 is made of a magnetic material, and magnetic pole pieces for alternately forming N and S magnetic poles in the circumferential direction of the inner peripheral portion (exemplified by 5 and 6 in the stator set 2, and in the stator set 3). 7 and 8) are alternately formed at small intervals, and a bobbin 10 having a large number of turns of the conducting wire 9 wound in a hollow portion therein is sandwiched.

These magnetic pole pieces 5, 6, 7, 8 are arranged and fixed in two stages vertically so as to be opposed to each other in the axial direction. The width of the pole pieces 5, 6, 7, 8 is formed to be equal to the (circumferential) pole width of the magnet rotor 11. The magnetic pole pieces 5 and 7 are respectively formed by extending the magnetic material portions on the lower surfaces of the stator sets 2 and 3 in the upward direction of the inner peripheral portion, and are formed so as to be offset from each other by a quarter pitch. Further, the magnetic pole pieces 6 and 8 are respectively formed by extending the magnetic body portions on the upper surfaces of the stator sets 2 and 3 in the downward direction of the inner peripheral portion, and are formed so as to be offset from each other by a quarter pitch. 12,13
Are lead wires connected to the conductor wires of the stator sets 2 and 3, respectively.

The cylindrical magnet rotor 11 is fixed to the rotating shaft 14 so as to rotate integrally. The magnet rotor 11 is supported by bearings 17 and 18 mounted on the flange 15 and the flange 16, respectively, whereby the magnet rotor 11 is rotatably arranged in the inner hollow portion of the stator 4. The magnet rotor 11 may be either a plastic magnet or a sintered magnet, and an appropriate one may be used. On the outer peripheral portion of the magnet rotor 11, N and S magnetic poles are alternately magnetized in multiple poles so as to face the magnetic pole pieces 5, 6, 7, and 8.

The magnet rotor 11 is formed so as to project from the lower end of the hollow portion of the stator set 3, and the Hall elements 20, 21 for energization control (see FIGS. 3 and 7) so as to face the outer circumferential surface of the projecting magnet rotor 11. (See the drawing), and lead wires 37 and 38 for Hall elements are installed from the respective Hall elements via the substrate.

The hall elements 20 and 21 are hollow cylindrical hall element positioning members 22 for escaping the magnet rotor 11 as shown in FIGS.
(22 = 23) It is attached to the upper cutout 24. As shown in FIG. 6 (b), the Hall element positioning member 22 has a notch 24 for fixing the Hall element, which is thicker than other portions so that the Hall element can be easily fixed. The part is thin so that the length of the motor in the direction of the rotation axis is not as long as possible, and as shown in the three-sided view (third method) in Fig. 7, the Hall element substrate 25 (25 = 26).
Is screwed on here.

FIG. 7 shows two Hall element positioning members 22 and 23 combined with each other with an angle difference of 82.5 °. 82.
The reason for setting the mechanical angle difference of 5 ° is as follows. In the motor of this embodiment having 48 comb-tooth-shaped portions per revolution, the pitch of the comb teeth is 360 ° / 48 = 7.5 °. Here, the 1/4 pitch deviation between the stator sets 2 and 3 is (2n-1) x 7.5 ° (n = 1,2,3, ..., 24), so when adjusting the Hall element With an angle of around 90 ° that makes it easy to operate, it is (2 × 12-1) × 7.
5 ° = 82.5 ° is set.

The Hall element positioning members 22 and 23 are provided with fan-shaped notches over 62 ° as shown in FIG. 6, and relative position adjustment is possible even if two Hall element positioning members are combined as shown in FIG. Is possible. Therefore, when adjusting the magnitude of the cogging torque, the phase difference of the comb tooth portion of the stator between the two stator sets 2 and 3 may be adjusted. In this case also, the Hall element should be adjusted to the stator. It is possible to move.

Two Hall element positioning members 22, 23 combined as shown in FIG. 7 are housed in the flange 16 as shown in FIG. In FIG. 4, 39 is a clearance hole for an assembly screw. Hall element positioning member 22,2 stored
Since 3 is slidable with respect to the flange 16, for example, 1
When 80 ° energization control is performed, stator set 2 and Hall element 21 and stator set 3 and Hall element 20 may be electrically in phase with each other, and when 90 ° energization control is performed, stator set 2 And Hall element 21, and stator set 3 and Hall element 20 are electrically
A phase difference of 45 ° (that is, a mechanical angle difference of 3.75 °) may be provided. Regardless of whether the 180 ° energization control or the 90 ° energization control is performed, the relative movement between the two Hall elements is effective against the cogging torque as described above.

The flange 16 incorporating the Hall element is assembled using the assembling screw 36 as shown in FIGS.

Further, as can be seen from the positional relationship between the magnetized surface of the magnet rotor 11 and the Hall element 20 shown in FIG. 3, the adjustment of the gap between them can be achieved simply by changing the Hall element positioning member 22 with the depth of the notch 24 changed. So it's easy.

The rotary shaft 14 is arranged so as to project from the lower end of the magnet rotor 11, and the magnetic encoder 28 in which N and S magnetic poles are alternately magnetized at a minute interval all around the periphery of the projecting portion of the rotary shaft 14 I am wearing. A magnetic sensor (MR element) 30 is provided at a position facing the magnetic encoder magnetic pole portion 29 (peripheral portion) so that the A-phase and B-phase signals are output with a 90 ° shift in electrical phase. The direction of rotation is detected by this electrical 90 ° phase shift. The speed control uses a rotor rotation speed signal obtained based on an output signal from one magnetic sensor (MR element).

The magnetic sensor (MR element) 30 is fixed to a mounting member 31 as shown in FIGS. 3 and 5, and can be moved on the MR element positioning member 32 by an adjusting screw 33. Therefore, the gap with the magnetic encoder magnetic pole portion 29 can be adjusted and fixed with the fixing screw 34. The output signal of the magnetic sensor (MR element) 30 is sent to a control circuit (not shown) via a lead wire 35 soldered on the mounting member 31.

The above-mentioned flange 16 is a magnetic sensor (MR element).
It also serves to prevent dust and dirt from adhering to the surfaces of the 30 and the encoder magnetic pole portion 29.

〔The invention's effect〕

As described above, in the present invention, the Hall element for controlling the energization of the exciting coil is arranged so as to be movable relative to each of the first and second stator sets (that is,
Since the electrical phase of the Hall element is adjustable with respect to the magnetic pole of the stator), 180 ° energization control and 90 ° energization control can be switched.

Further, since the present invention is configured based on the stator set of the PM type stepping motor, it suffices to install the exciting coil (for example, 3C shown in FIG. 8) between the outer stator and the inner stator produced by pressing. Good. Therefore,
The coil can be easily replaced, and the resistance value can be changed.

Further, the coil itself can be easily manufactured by simply winding the conductor wire around the bobbin, and the stator is also manufactured by pressing, which is excellent in mass productivity and advantageous in cost.

Moreover, since the Hall element included in the present invention is movably arranged, it is necessary to adjust the magnitude of the cogging torque, so that the phase difference of the comb tooth portion of the stator between the two-phase stator sets is adjusted. , It is possible to easily adjust the position of the Hall element with respect to each stator set.

[Brief description of the drawings]

1 to 3 are perspective views, partially broken perspective views and sectional views, respectively, of a multi-pole brushless motor according to an embodiment of the present invention. FIG. 4 is a Hall element and a second flange. Figure showing the positional relationship, Figure 5 is a perspective view showing the installation portion of the magnetic sensor (MR element), Figure 6 is a trihedral view of the Hall element positioning member by the trigonometric method, and Figure 7 is two Hall element positioning members. Fig. 8 is a trigonometric three-dimensional view showing the positional relationship among them, Fig. 8 is a view showing the relationship between the stator and the coil of a stepping motor, Fig. 9 is a structural diagram of an outer rotor type of a conventional brushless DC motor, and Fig. 10 is Fig. 11 is a structural diagram of a conventional brushless DC motor inner rotor type, Fig. 11 is a structural diagram of a conventional brushless DC motor slot type stator, and Fig. 12 is a structural diagram of a conventional brushless DC motor slotless type stator. You. 2,3 …… stator set, 3a …… inner stator, 3b …… outer stator, 3c …… excitation coil, 11 …… magnet rotor, 14 …… rotating shaft, 15,16 …… flange, 20,21… … Hall element, 22,23 …… Hall element positioning member, 25,26 ……
Hall element substrate, 24 ... Notch for fixing Hall element, 27 ...
... Fan-shaped notch for combination of Hall element positioning members, 28
...... Magnetic encoder, 29 ...... Magnetic encoder magnetic pole part, 30
...... Magnetic sensor (MR element), 31 …… MR element mounting member, 32
…… MR element positioning member, 33 …… MR element adjustment screw, 34
…… MR element fixing screw.

Claims (1)

(57) [Claims] 1. A rotor having magnetic poles on a peripheral surface at a predetermined pitch, and a first rotor having comb-shaped portions at the predetermined pitch and being offset from each other by 1/4 pitch with respect to the rotor. And a second stator set, coils for exciting the first and second stator sets, and first and second holes arranged to face the magnetic pole surface of the rotor for controlling energization of the coils. An element and first and second Hall element positioning members capable of adjusting the relative positions of the first and second Hall elements, and the relative positioning of the first and second Hall element positioning members. A multi-pole brushless motor characterized by switching 180 ° energization control and 90 ° energization control by adjusting the position.