JP2584804B2 - Stepping motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a stepping motor having an anisotropic resin magnet rotor and a stator yoke.

[Prior art] Conventionally, in a small stepping motor or the like,
A multi-pole oriented plastic magnet rotor made of a thermoplastic resin is used, and a small-sized PM step motor formed by two-color molding with a shaft, press-fitting, bonding, or the like is generally used.

[Problems to be solved by the invention] However, with the miniaturization of this type of motor,
As the structure of the motor is also reduced from the conventional general configuration of the two-stage stacking of each phase to more miniaturization, the stator yokes are arranged on the left and right sides of the rotor, irregularly, and There are many proposals that are arranged in accordance with the product.However, due to the difference in the gap between the left and right stator yokes, the angular position of the stator teeth, and the eccentricity of the rotor itself, etc. There has been a problem that the balance of the amount of magnetic flux is lost, so that a stable stop position in design cannot be obtained, and torque unevenness occurs.

The present invention seeks to solve the above problems.

[Means for Solving the Problems] In order to solve the problems described above, according to the present invention, a rotor composed of a cylindrical anisotropic resin magnet having N magnetic poles and S magnetic poles alternately arranged in a circumferential direction, In a stepping motor having a plurality of stator yokes arranged in the circumferential direction of the rotor and a coil for exciting these stator yokes,
Within each magnetic pole on the peripheral surface of the rotor (for example, magnetic pole center)
In addition, a concave portion extending in the axial direction of the rotor is formed so that the magnetized waveform of the rotor is substantially trapezoidal (for example, a two-headed waveform).

[Operation] According to the present invention, the rotor is disposed long in the axial direction, and the stator is formed at a position opposed to the left and right sides of the rotor in which a concave portion is formed in the magnetic pole center of the rotor so that the magnetized waveform has a substantially trapezoidal waveform. By arranging stator yokes having teeth and providing coils for generating a magnetic field in these stator yokes, it is possible to reduce the size and weight of the entire motor, and to conform to the product space, irregular, and Since the rotor is freely arranged, the degree of freedom in design is wide, and the rotor is downsized, the moment of inertia can be reduced and sufficient torque can be obtained.

By performing trapezoidal magnetization, a harmonic component is included in the cogging torque characteristic generated between the rotor and the stator.

In other words, the cogging torque characteristic generated between one set of the left and right stators and the rotor is T _C1 = a ₁ sin2Pθ (where P is the number of magnetic pole pairs of the rotor, θ can be expressed by the angle of the rotor with respect to the point where the center of the magnetic poles of the rotor and the stator coincide with each other. However, when the rotor magnetization is a double head wave, a second harmonic component is added, and T _C1 = A ₁ sin2Pθ + a ₂ sin4Pθ (a ₁ > a ₂ ).

On the other hand, the cogging torque characteristic generated between the other stator set and the rotor is shifted from each other by 1/4 of the magnetic pole pitch. Can be represented by Cogging torque T _C of the motor, because it is determined by the sum of T _C1 and T _C2, the _{T C = (a 1 -b 1} ) sin2Pθ + (a 2 + b 2) sin4Pθ. The primary component of the cogging torque cancels out the difference between the two stator sets, whereas the secondary component is summed and emphasized. Therefore, by performing trapezoidal or two-headed magnetizing, the rotor can be stopped twice as much as before, and the size of cogging itself can be reduced, so that the stop position accuracy due to stable fine cogging is improved, and torque unevenness is improved. , And the controllability can be improved with excellent startability and responsiveness.

Embodiment FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a rotor having a plurality of magnetic poles N and magnetic poles S alternately magnetized on an outer peripheral surface, and 1A denotes a rotor shaft thereof. The rotor shaft 1A is supported by a bearing 2A of the motor support plate 2 and a bearing 3A of the bearing plate 3. The support plate 2 and the bearing plate 3 have a plurality of comb-shaped teeth. Yoke members 5L1, 5L2 having a stator 4 and an iron core 7 around which a coil 6A is wound, and similar yoke members 5R1, 5R2
And the iron core 8 around which the coil 6B is wound are fixed by caulking or screwing, respectively.

Reference numerals 2B and 3B denote holes formed in the support plate 2 and the bearing plate 3 for penetrating the iron core 7 and the iron core 8 and then caulking the ends thereof, and 5A denotes a caulking for fixing the yoke member 5. Hole.

FIG. 2 (A) is a plan view of a multi-pole anisotropically-oriented resin magnet rotor. As shown, the multi-pole rotor has a concave portion formed at the center of the magnetic pole of each of the N and S poles. It can be seen that sparse portions and dense portions are formed by providing the concave portions.

By arranging the stator yoke having the stator teeth opposed to the rotor formed in this way in a magnetic field in which the air gap is in the range of 0.1 to 0.2 mm in a densely and densely distributed magnetic field, as shown in FIG. 2 (B). It can be seen that a two-headed (substantially trapezoidal) magnetization waveform is obtained.

Next, the operation of the stepping motor thus configured will be described with reference to FIGS. 3 (a), 3 (b) and 3 (b).
This will be described with reference to FIG.

That is, in the stepping motor of this embodiment, the rotor 1 rotates by 1 / 4P (P = pitch) in four stages of (a) → (b) → (c) → (d) in FIG. Fig. 3 (a) shows the coil 6A and the coil
6B shows the state of the motor that is not energized. In this case, since the magnetic poles provided on the rotor 1 form a magnetic path via the stator 4 and the yoke member 5, the stator teeth 4L1 and The stator teeth 4L2 of the yoke member 5L2 face the magnetic pole S and the magnetic pole N of the rotor 1, respectively, and are stopped.

On the other hand, the stator teeth 4R1 of the right yoke member 5R1 and the stator teeth 4R2 of the yoke member 5R2 do not face the magnetic pole S and the magnetic pole N of the rotor 1 and are in a state of being shifted by a half pole, that is, 1 / 2P. Thus, the right yoke phase and the left yoke phase are set so as to be shifted by 1 / 2P.

That is, the pitch P is the pitch of the magnetized magnetic poles in the rotor 1, and in this case, the angle θ shown in the drawing is θ
= NP + 1 / 2P, and the yoke member 5L1,
Pitch between stator teeth 4L1 and 4L2 constituted by 5L2 and stator teeth 4 constituted by yoke members 5R1 and 5R2
The pitch between R1 and 4R2 matches the pitch P described above.

Next, as shown in (b) from the state of FIG. 3 (a), when the coil 6A is energized in the reverse direction (this state is indicated by B), and when the coil 6B is energized in the forward direction (this state is shown). A
The stator tooth 4L1 has an N pole, and the stator tooth 4L1 has
An S pole is generated at L2, and an S pole is generated at the stator tooth 4R1 and an N pole is generated at the stator tooth 4R2. In this manner, the rotor 1 can be rotated in a counterclockwise direction by mutual repulsion and suction between the poles of the rotor 1 and the poles generated in the individual stators. That is,
At this time, since the left stator teeth 4L1 and 4L2 and the right stator teeth 4R1 and 4R2 are displaced by 1 / 2P, the poles of the rotor 1 and the poles on the yoke side are kept in balance in FIG. After moving by 1 / 4P in the counterclockwise direction from the state of b), stop stably.

Next, in the state shown in FIG. 3 (b), the energization of the coil 6A is stopped, and the energization is continued only for the coil 6B to obtain the state shown in FIG. 3 (c). As a result, the stator tooth 4R1 has the S pole and the stator tooth 4R2. Is maintained at the N pole, so that the opposing rotor 1
The rotor 1 further rotates in the counterclockwise direction by 1 / 4P due to the suction operation between the first and second poles.

Then, in the state shown in FIG. 3 (c), by energizing the coil 6A in the positive direction as shown in FIG. 3 (d), the rotor 1 is further counterclockwise rotated by 1 / 4P in the same principle. It can be turned around.

A series of operation procedures described above will be further described with reference to FIG. Here, the abscissa indicates the sequence of steps, and further shows the energized state of the coils 6A and 6B for each step. That is, steps S1, S2, S3, S4, S
5, S6, S7, S8, there are eight combinations of energization from BA to B. These eight steps are sequenced as one pulse, and the rotor 1 can be arbitrarily selected by repeating the steps. Can be rotated to an angle. Further, by controlling the energization so that the above-described combination of the energizations proceeds in reverse, the rotor 1 can be rotated in the clockwise direction.

[Effects of the Invention] As described above, according to the present invention, a concave portion such as a concave or V-shaped groove is formed in each magnetic pole (for example, the center) of a rotor serving as a rotor of a motor. Since the magnetized waveform of the rotor is provided with an anisotropic resin magnet rotor having a substantially trapezoidal waveform such as a two-headed waveform, the stopping position accuracy is improved by stable fine coking as designed, that is, as designed. As a result, a stable motor characteristic with less torque unevenness can be obtained, and excellent startability and control function can be maintained. Therefore, an efficient small and lightweight stepping motor can be provided. Further, it is very easy to form the stepping motor long in the axial direction, and it is possible to provide a stepping motor having a small size, a small moment of inertia, and a high torque.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of the present invention, FIG. 2 (A) is a sectional view of the rotor of FIG. 1, FIG. Figures (a), (b), (c),
(D) is an explanatory view of the operation of the stepping motor of FIG. 1,
FIG. 4 is an explanatory diagram of the timing of the excitation sequence. 1 ... rotor 2 ... motor support plate 3 ... bearing plate 4 (4L1, 4L2, 4R1, 4R2) ... stator teeth 5 (5L1, 5L2, 5R1, 5R2) ... yoke member 6, 7 ... coil , 8,9 ... iron core

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Yoshikawa 1248 Shimokagemori, Chichibu City, Saitama Prefecture Inside Canon Electronics Co., Ltd. (56) References JP-A-61-22751 (JP, A) 11980 (JP, U) Actually open sho 61-171470 (JP, U)

Claims (1)

(57) [Claims] 1. A rotor comprising a cylindrical anisotropic resin magnet having N magnetic poles and S magnetic poles alternately arranged in the circumferential direction, a plurality of stator yokes arranged in the circumferential direction of the rotor, and exciting these stator yokes. A stepping motor, comprising: a stepped motor having a coil extending in a magnetic pole on a peripheral surface of the rotor.