JP2640938B2 - Electric motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric motor such as a three-phase brushless motor.

[Conventional technology and its problems]

In general, motors with low power consumption, small size and thin type are often required, and it is necessary to keep the starting current low from the viewpoint of low power consumption. On the other hand, if the starting current is low, the starting torque also decreases in proportion thereto. For this reason,
The ratio between the torque generated when the coil wound on the stator of the electric motor is excited and the cogging torque when the coil is not excited becomes very large, and a smooth start cannot be realized with a low power consumption. There was a problem.

Therefore, an object of the present invention is to provide a motor that can be started smoothly even with low power consumption and that can be reduced in size and thickness.

[Means for solving the problem]

In order to achieve the above object, an electric motor according to the present invention comprises a multi-pole magnetized rotor magnet, and a stator in which a multi-phase coil is wound facing the rotor magnet. In addition, a plurality of large teeth are arranged at the same pitch around the circumference, and among the slots formed between the large teeth, slots other than the number of phases of the coil are arranged in other slots for each phase. With small teeth, in each phase,
A coil is continuously wound around at least one small tooth together with a large tooth, and a rotor position detector is arranged in each slot where no small tooth is present.

[Action]

In the electric motor having the above-described configuration, since the small teeth are provided between the plurality of large teeth of the stator, the cogging torque is extremely small, and the coil is wound around the small teeth for each phase together with the large teeth. Since the coil is turned, the large teeth and the small teeth are magnetized by energizing the coil, which can greatly contribute to the generation of rotational force on the rotor magnet, and can generate a large starting torque at the time of starting.

Further, among the slots between the large teeth, a slot in which the small teeth are not provided is formed, and the rotor position detector is housed in this slot, so that this detector is disposed outside the rotor in the axial direction. The dimension in the axial direction can be reduced, which is extremely advantageous in reducing the thickness.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

FIG. 1 shows an electric motor according to the present invention.
This motor has a housing 2 having a cylindrical portion 1 at a substantially central portion, a rotor housing 3 rotatably supported by the cylindrical portion 1 of the housing 2, and a multi-pole magnetized attachment to the rotor housing 3. The rotor magnet 4 includes a stator 5 fixed to the housing 2 so as to be fitted into the rotor magnet 4.

The rotor housing 3 includes a disk 7 having a rising portion 6 on the outer periphery, and a shaft 11 having one end fixed to a substantially central portion of the disk 7 and rotatably inserted into the cylindrical portion 1 of the housing 2. The ring-shaped rotor magnet 4 is fixed to the inner peripheral surface of the rising portion 6. As shown in FIG. 2, the rotor magnet 4 is magnetized on its inner side in order of N pole, S pole, N pole, S pole.

Further, the stator 5 has six large teeth 8a, 8b, 8c, 8d, 8e, 8 that are closely opposed to the inside of the rotor magnet 4 every 60 degrees of the central angle.
f, and slots 9a, 9b, 9c, 9d, 9e, 9f formed between the large teeth 8a, 8b,... Teeth 10b, 10d, 10f
Is formed. The stator 5 is formed by laminating one or two or more thin-plate stator laminations 12 having large teeth and small teeth as shown in FIG. (Note that, in the illustrated example, a plurality of sheets are superposed and laminated.) The shaft hole 13 of the stator 5 is fitted and fixed to the cylindrical portion 1 of the housing 2.

On the large teeth 8a and small teeth 10b of the stator 5, coils 14 for three phases are wound for each phase. That is, as shown in FIG. 2, the first phase is successively wound around the large teeth 8a, the small teeth 10b, and the large teeth 8d in succession. The eyes are sequentially wound around the large teeth 8c, the small teeth 10d, and the large teeth 8f, and the third phase is successively wound around the large teeth 8e, the small teeth 10f, and the large teeth 8b. Then, the motor is rotated by sequentially energizing them in accordance with the rotational position of the rotor magnet 4.

Further, three rotor position detectors 15 for detecting the position of the rotor magnet 4 are formed of Hall elements or the like, and are fixed in three slots 9a, 9c, 9e having no small teeth. Reference numeral 16 denotes a printed wiring board to which the coil 14, the rotor position detector 15, and the like are connected. The printed wiring board 16 is attached to the back surface 17 of the housing 2. Reference numeral 18 denotes a bearing interposed between the shaft 11 and the inner peripheral surface of the cylindrical portion 1.

The waveform of the cogging torque generated by this motor is as shown in FIG. 4 (I), which is smaller in amplitude than the cogging torque of the conventional motor without small teeth shown in FIG. 2 (II). Becomes

Thus, in the above-described electric motor, the number of the magnetic pole pairs of the rotor magnet 4 is P, the number of the large teeth 8a is N / 2, and the large teeth 8a
When the tooth pitch of... Is α and the tooth pitch of the small teeth 10b is β, α is an effective electrical angle of about π radian and β is an effective electrical angle of about (2P−N / 2) × 2π / N
Radians. The small teeth 10b ...
The number determined by the number of phases of 4 is omitted at predetermined intervals (every 120 degrees in the example in the figure). In the example shown, the small teeth 10
a, 10c, and 10e are omitted. That is, in this case, P =
4, since N / 2 = 6, if (2P−N / 2) × 2π / N (that is, the tooth pitch β of the small teeth) is π / 3 radian, the mechanical angle becomes π / 4 radian, and If the angle is π / 3 radians, the mechanical angle is π / 12 radians.

Here, the number of large teeth of the stator 5 used in the present invention,
The relationship between the number of magnetic pole pairs of the rotor and the angle pitch of the omitted small teeth is as shown in Tables I and II.

Table I shows the case of three-phase unipolar or three-phase bipolar. For example, when the number of large teeth 8 of the stator 5 is 6, and the number of magnetic pole pairs of the rotor magnet 4 is 4, small teeth 10a are shown in FIG. As shown in FIG. 5, three (for the number of phases of the coil) may be omitted every 120 degrees, or three may be continuously omitted every 60 degrees as shown in FIG. Note that twice the angle of the omitted small teeth must not be greater than 360 degrees. Here, as shown in FIG. 5, the winding of the coil 14 in the case of FIG. 5 is such that the large tooth 8a, the large tooth 8d, and the small tooth 10e are successively wound in this order as shown in FIG. The eye and the third phase are not shown, but the second phase is sequentially wound around the large teeth 8b, the large teeth 8e, and the small teeth 10f, and the third phase is the large teeth 8c, the large teeth 8f, and the small teeth 10d
It is wound continuously in order.

Table II shows the case of two-phase bipolar or four-phase unipolar. For example, when the number of large teeth 8 of the stator 5 is four and the number of rotor magnet pole pairs is three, small teeth 10a. This means that two or two may be omitted at intervals of 270 degrees. In addition, the angle of the omitted small teeth is
Should not be larger than 360 degrees.

Next, FIG. 3 shows a comparative example, in which all slots 9a are provided with small teeth 10a. That is, the small teeth 10a, 10c and 10e are also provided in the slots 9a, 9c and 9e of the stator 5 shown in FIG. The large teeth 8a and small teeth 10a of the stator 5 are formed.
As shown in FIG. 2, coils 14 for three phases are wound around. That is, in the first phase, the large teeth 8a, the small teeth 10b, the large teeth 8d, and the small teeth 10
e, the second phase and the third phase are not shown, but the second phase is wound around the large teeth 8b, the small teeth 10c, the large teeth 8e, and the small teeth 10f.
The phase is wound around the large teeth 8c, the small teeth 10d, the large teeth 8f, and the small teeth 10a.

Therefore, in the case of this comparative example, the rotor position detectors 15 ...
1 must be provided between the printed wiring board 16 and the rotor holder 6, the rotor magnet 4, the stator 5, the coil 14, etc. in FIG. 1, and the dimensions of these spaces cannot be set small. That is, this motor cannot be made very thin. On the other hand, in the embodiment according to the present invention as shown in FIG. 2, the rotor position detector 15 can be attached to the slots 9a, 9c, 9e where the small teeth 10a, 10c, 10e are omitted. The motor can be made as thin as possible.

Further, in the case of the comparative example, it is difficult to secure a space for soldering the coil 14 to the substrate 16, whereas in the embodiment according to the present invention as shown in FIG. 2, the small teeth 10a, 10c, 10e Since there are slots 9a, 9c, and 9e that do not have the holes, a sufficient space for soldering can be secured.

The number of turns of the coil 14 shown in the example and the comparative example is simplified, but is actually large. Further, as shown in Tables I and II, this motor can be of course a bipolar type or a unipolar type, and the number of phases and the number of poles are free. Outer rotor type is free.

Further, in the embodiment, the coil 14 is wound around all the existing small teeth 10, but there may be small teeth 10 (at least one winding is sufficient) where the coil 14 is not wound. . It is more preferable that the coil 14 is wound around all the small teeth 10.

Here, when the stator 5 according to the present invention is formed, small teeth 10a are omitted at predetermined intervals from all the slots 9a provided with small teeth 10a as shown in the comparative example. Therefore, there are various omission methods as shown in FIG. That is, in FIG. 6 (I), only the front end is omitted, in FIG. 6 (II), the small teeth 10 are omitted from the substantially middle part to the front end, and in FIG. 6 (III), the whole is omitted. .

In addition, since it is formed as a substantially T-shape with the small teeth 10, the width of the front flange is reduced by slightly notching the front flange, and the clearance between the small teeth 10 and the magnet 4 is reduced. Larger values are possible, and in this case also the object of the present invention can be achieved. In addition, it is of course possible to cut out only the tip flange.

〔The invention's effect〕

The present invention is configured as described above, and has the following effects.

Because small teeth are provided between the large teeth of the stator,
Because the cogging torque is extremely small, and the coil is continuously wound with the large teeth on the small teeth for each phase,
The energization of the coil magnetizes the large teeth as well as the small teeth, which can greatly contribute to the generation of rotational force on the rotor magnet, and can generate a large start-up torque at start-up. What you can get.

Further, among the slots between the large teeth, a slot in which the small teeth are not provided is formed, and the rotor position detector is housed in this slot, so that this detector is disposed outside the rotor in the axial direction. The size in the axial direction can be reduced, so that the overall size and thickness can be reduced, and the use of the slots facilitates the work of soldering the lead wires of the coil.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention, FIG. 2 is a simplified plan view of a stator and a rotor magnet, FIG. 3 is a simplified plan view of a stator and a rotor magnet showing a comparative example,
FIG. 4 is a waveform diagram of cogging torque generated from the motor of the embodiment and the conventional example, FIG. 5 is a simplified plan view of a stator and a rotor magnet showing another embodiment, and FIG. 6 is a plan view of small teeth in various states. FIG. 4 ... rotor magnet, 5 ... stator, 8a ... large teeth, 9a ... slots, 10a ... small teeth, α, β ... teeth pitch.

 ──────────────────────────────────────────────────続 き Continuing on the front page Judge Kazuyuki Shimono Judge Tadayuki Watanabe Judge Hikaru Ito (56) References JP-A-59-61460 (JP, A)

Claims (2)

(57) [Claims] A multi-pole magnetized rotor magnet and a multi-phase coil arranged opposite to the rotor magnet.
Are wound around the stator 5, wherein a plurality of large teeth 8 a are arranged on the stator 5 at a constant pitch around the circumference, and between the large teeth 8 a. Out of the slots 9a, 9b, 9c (9a, 9b, 9c) of the number of phases of the coil 14, small teeth 10b for each phase are provided. , In each phase, the coil 1
4 is continuously wound around the at least one small tooth 10b with the large tooth 10a, and is inserted into each of the slots 9a, 9c, 9e (9a, 9b, 9c) where the small tooth 10b is not present. An electric motor, wherein a rotor position detector 15 is arranged. 2. The number of magnetic pole pairs of the rotor magnet 4 is P,
When the number of the large teeth 8a is N / 2, the tooth pitch α of the large teeth 8a becomes approximately π radian in the effective electrical angle, and the tooth pitch β of the small teeth 10a becomes the effective electrical angle. 2. The electric motor according to claim 1, wherein the electric power is about (2P−N / 2) × 2π / N radians.