JPS6331454A - Motor - Google Patents

Abstract

PURPOSE:To reduce variations in torque and speed of a motor by unequally setting the circumferential pitch of the poles of a rotor for a motor. CONSTITUTION:A rotor 3 having an output shaft 2 is rotatably supported in a cylindrical stator unit 1, and a flange 4 for attaching a motor is secured to one end of the unit 1. The unit 1 is formed by bonding two stators 5 disposed adjacently in the direction of the shaft 2, and the stators are composed of outer and inner stators 6 and 7 and coils 8. A plurality of outer and inner stator poles 9, 10 projecting axially are formed at predetermined intervals in the circumferential direction on the inner peripheries of the stators 6 and 7. Further, the rotor 3 is formed in a permanent magnet type, and a plurality of poles N, S are arranged in the circumferential direction. In this case, the stator poles 9 and 10 engaged with one another are formed at an equal interval (equal pitch) in the circumferential direction, and the poles of the rotor 3 are disposed at an unequal interval (unequal pitch) in the circumferential direction. Thus, the cogging torque of the whole motor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a motor equipped with a stator having stator balls forming a magnetic path and a permanent magnet rotor.

[Prior Art] This type of motor includes a stepping motor and a rutn motor. In the case of a stepping motor, the pole teeth (stator balls) of a stator having a plurality of excitation phases (excitation coils) are opposed to the magnetic poles of a rotor. , the rotor is configured to rotate in a predetermined direction by a predetermined angle by inputting pulses to each excitation phase in a predetermined order.

Therefore, the rotation angle of the rotor from its initial position is proportional to the number of input pulses, and the rotational position of the stepping motor is controlled by these input pulses.

Furthermore, this stepping motor is constructed by supporting a rotor having multiple magnetic poles within a stator having multiple pole teeth (stator balls) excited by a coil. VR (variable relaxation) type with salient poles on the surface, PM (with permanent magnet in the rotor)
The motor can be divided into a permanent magnet type, a hybrid PM type which is a combination of the VR type and the PM type, and the present invention is especially applicable to PM type stepping motors.

The PM type stepping motor has a stator having a plurality of stator balls (stator pole teeth) arranged in the circumferential direction and a coil wound around each stator ball to generate magnetic flux, and an outer stator. It is composed of a permanent magnet type rotor having a plurality of magnetic poles on the outer peripheral surface opposite to the inner peripheral surface.

By the way, when operating this type of motor, when accelerating to a certain speed (constant pulse period input) and making it continue to rotate with constant pulse period input, each excitation phase must be sequentially controlled within the positive torque range! JIJ is switched to accelerate, and in the - constant pulse period manual power region, the switching torque integral value is set to zero so as to balance the positive and negative torques of each excitation phase to produce a constant speed drive state.

In this constant speed drive state, even though the speed is constant, speed fluctuations occur due to positive and negative fluctuations in torque at every pulse period.

On the other hand, in a conventional motor of this kind, the circumferential pinch of the stator ball and the circumferential pinch of the Fa pole of the rotor are both set at equal pitches, and from their positional relationship, the angle-torque characteristic (θ- Since the T characteristic) is a repeating almost sinusoidal waveform, the slope of the torque curve near the torque zero point is large, and the speed fluctuation caused by positive and negative torques is large.In addition, the rotor's magnetized magnetic pole pitch and the teeth of the stator ball Since the pitch is the same for all phases, many magnetized magnetic poles and stator balls always occupy positions facing each other, and the residual torque (cogging torque or detent torque) is extremely large in the 1st direction. there were.

Therefore, in conventional motors, smooth rotation is hindered due to the large speed change near the torque zero point and the presence of large residual torque, resulting in unstable load motion and noise generation. There were other problems.

[Objective 1] The object of the present invention is to solve the problems of the prior art, reduce the residual torque of the motor, and reduce torque fluctuations and speed fluctuations during constant speed rotation, thereby operating stably and smoothly. The purpose is to provide motors.

[Means for Achieving the Object] The present invention provides a stator having a plurality of stator balls arranged in the circumferential direction and a coil wound around each stator ball to generate magnetic flux, and a stator of the stator. In a motor composed of a permanent magnet rotor having a plurality of magnetic poles on the outer circumferential surface facing the inner circumferential surface, the above purpose can be achieved by making the circumference and notch of each magnetic pole of the rotor unequal. It is something to be achieved.

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 1 shows an r'M type stepping motor suitable for applying the present invention, and FIG. 2 shows the outer stator in FIG.
FIG. 3 shows the rotors in FIG. 1, respectively.

In FIG. 1, a rotor 3 having an output shaft 2 is rotatably supported inside a cylindrical stator unit 1, and a flange 4 for mounting a motor is attached to -,%j:j of the stator unit 1. is fixed.

The stator unit 1 has a divided structure in which two stators 5.5 are joined together and arranged in a V1 manner in the direction of the output shaft 2. Each stator 5.5 has a similar structure and is constructed by assembling an outer stator 6, an inner stator 7 and a coil 8, respectively.

As shown in FIG. 2, the inner circumferential portion of the outer stator 6 has:
A plurality of outer stator balls 9 are formed to protrude in the axial direction at predetermined intervals in the circumferential direction, and the inner circumferential portion of the inner stator 7 has projections and depressions facing each of the outer stator balls 9 with a predetermined gap. A plurality of inner stator balls 10 are formed that protrude in the axial direction.

The coil 8 is arranged so as to form a plurality of excitation phases.
It is wound around the inner stator balls 9.10 and arranged to generate magnetic flux in each stator ball 9.10 in a predetermined sequence.

The rotor 3 is a permanent magnet type rotor, and its outer circumferential surface, that is, the outer circumferential surface facing the inner diameter of the stator 5.5 with a predetermined gap, has a plurality of magnetic poles ( N pole, S pole) N and S are arranged.

As described above, by rotatably supporting the permanent magnet rotor 3 within a pair of stators 5.5 and sequentially exciting the plurality of coils (excitation phase) 8 wound around each stator at a predetermined timing. , the output shaft 2 is configured to rotate in a desired direction at a desired speed.

In addition, each stator 5.5 can be formed, for example, by press forming or deep drawing of a T4 plate.

In order to drive the EPM type stenoping mode one after another at a desired pulse timing, for example, drive control as described below is required.

Figure 4 shows the excitation phase with bifilar winding in a 4-phase stepping motor, with numbers 11 and 12 in Figure 4.
．． 13.14 are the 1st phase, 2nd phase, 3rd phase, and 4th phase, respectively.
The phase winding coils are shown, and numbers 15, 16, 17, and 18 indicate the respective sum driving transistors.

In FIG. 4, by applying a drive command signal from a control circuit (not shown) to the base of each drive transistor 15, 16, 17, and 18 at a predetermined timing and in a predetermined sequence, the corresponding wire-wound coil is 11.12.13.1
Driving voltage VD is applied to 4.

Figure 5 (Δ) and (B) show 2-2 phase excitation and 1-
A time chart of the drive command signals of the first to fourth phases in the case of one-phase excitation is illustrated.

FIG. 6 illustrates the angle-torque characteristic (θ-T characteristic) generated by the 1-1 phase excitation and the 2-2 sum excitation.

In Fig. 6, symbols I, ■, ■, and ■ indicate the θ-T characteristics of 1-1 phase excitation in which only the 1st, 2nd, 3rd, and 4th phase winding coils are excited, respectively. , If is 2 when the first phase winding coil and the second phase winding coil are simultaneously excited.
- Shows the θ-T characteristics of two-phase excitation.

2-2 phase excitation corresponds to the case where two phases are simultaneously excited in 1-1 phase excitation, so the 111 curve is 1
It can be expressed as the sum of the curve and ■curve.

In addition, in the graph of FIG. 6, for 2-2 phase excitation, I
Only the θ-T characteristics of II are shown.

Figures 7 (A) and (B) show that the motor is driven by the 1-1 phase excitation in Figure 6, accelerates to a certain speed (constant pulse cycle input), and then maintains this constant speed and rotates. FIG. 7(A) shows the speed characteristics of the rotor over time, and FIG. 7(B)
) indicates the θ-T characteristic and phase switching timing at that time.

As shown in FIG. 7(B), switching time t=Q, tl, t
2, by sequentially switching from phase I to phase ■ to phase ■, positive torque is applied to accelerate, and in the constant pulse period input region, the positive and negative torques (hatched area in Fig. 7 (B)) cancel each other out. A so-called constant-speed drive state is maintained by controlling the motor to maintain balance.

In driving such a stamping motor, the seventh
As is clear from the figures <A) and (B), even though it is called constant speed, the actual switching timing is t3, t4...
-... A slight speed fluctuation dω occurs every time.

However, in the conventional PM type stepping motor,
As shown in the developed schematic diagram of FIG. 8, the stator balls 9.10 of the stator 5.5 are arranged at equal pitches in the circumferential direction, and the magnets 14N and S of the rotor 3 are also arranged at equal pitches in the circumferential direction. Because they were arranged at intervals, the θ-T characteristic is a repeating almost sinusoidal waveform due to their positional relationship, so the rate of torque change near the torque zero point is large, and the speed fluctuation caused by positive and negative torque fluctuations is also large. It was a value.

Roughly, as is clear from the schematic diagram of the stator ball section and rotor shaft in Figure 8, the stator ball 9.10
Teeth pitch and rotor 3 wear tf! Since all phases are the same, there are always many magnetized magnets +i =
As a result, the stator balls and stator balls are positioned opposite to each other, and residual torque (cogging torque or detent torque) tends to become extremely large.

In addition, by providing a pair of stators 5.5 as shown in FIGS. 1 and 8, and selecting the phase and amplitude of the residual torque of each stator to be symmetrical in positive and negative, the residual torque of the motor can be reduced to zero. However, in reality, as is clear from the mechanism of residual torque generation described below, it is difficult to reduce the residual torque simply by providing a pair of stators 5.5.

First, when the magnetization pinch of the rotor 3 and the indexing angle of the stator 5.5 are arranged at the same pinch as shown in Fig. 8, the residual torque in each stator 5.5 is as shown by curves A and B in Fig. 9. is expressed in

By the way, the residual torque that appears in the entire motor is the residual torque A generated from one stator 5 and the other stator 5.
If both stators 5.5 were configured completely uniformly, the residual torque A and the residual torque B would cancel each other out, and the residual torque appearing in the entire motor would be zero. It should be.

However, normally, it is unavoidable that some kind of imbalance occurs such as magnetization error or machining accuracy of the rotor 3, and as shown in FIGS. 10(A) and (B), the residual torque A of each stator 5.5, Due to the unbalance of B, residual torques X and Y are generated as the sum thereof.

In addition, FIG. 10 (Δ) shows the case where the phases of the residual torques A and B of both stators 5.5 are the same, and FIG.
B) shows the case where the amplitudes and phases of the residual torques A, , B are different.

As described above, in the conventional PM type stepping motor, even if the pair of stators 5.5 are arranged symmetrically, it is virtually impossible to reduce the residual torque, and the motor rotation may become unsmooth or This was causing unstable load-bearing operation and noise.

FIG. 11 is a schematic exploded view of a stator ball portion and a rotor portion of a PM type stepping motor according to the present invention.

FIG. 11 shows a stator unit 1 as shown in FIG. 1 constructed by arranging two stators 5 connected in the axial direction and having a structure in which a plurality of outer stator poles 9 and inner stator poles 10 are opposed to each other in a meshing state. Here is an example of a case where

A rotor 3, in which a plurality of magnetized magnetic poles N and S are alternately formed at predetermined intervals in the circumferential direction, is rotatably supported within the inner diameter of the stator unit 1.

According to the present invention, as shown in FIG. 11, the stator balls 9.10 that are jetted into each other in each stator 5.5 are formed at equal intervals (equal pitch) in the circumferential direction; The plurality of magnetic poles N and S of the rotor 3 are arranged at unequal intervals (unequal pitch) in the circumferential direction.

The unequal pitch arrangement of the magnetized magnetic poles N and S may be, for example, an arrangement in which each interval changes in size equimetrically in a sinusoidal manner, or an arrangement in which each interval is sequentially arranged in a geometric series or equidistant order. An arrangement that changes in size is adopted.

Figure 12 shows the n-th magnetized magnetic pole on the circumferential surface of the rotor 3 and (n-
, 1) exemplifies the change characteristics of the distance ni between the C magnetic pole and the C magnetic pole.

As explained above, the plurality of magnetized magnetic poles N, S of the rotor 3
By arranging them at unequal pitches in the circumferential direction, even within the same phase, the magnetized magnetic poles N,
The number of pairs of S and stator ball 9.10 could be significantly reduced, and the residual torque (cogging torque) of the entire motor could also be significantly reduced.

For example, as shown in FIG. 10 (8) and (B), the imbalance between the pair of stators 5.5 and the magnetization t1 of the rotor
If residual torques X and Y occur due to differences, etc., the rotor 3's ? By shifting the circumferential pitch (phase) of the seven magnetic poles, it was possible to reduce the residual torque of the entire motor more effectively, such as by reducing it to zero or significantly reducing it.

In other words, the fitting of the rotor 3 is adjusted according to the dimensions of the stator 5.5 and rotor 3 and the pattern of errors in assembly.
, 'fi (N, S), etc., the residual ]-lux can be effectively reduced.

For example, as shown in Fig. 10 (I3), if the amplitude IIJ and phase of the K + 5 torques A and B of both stators 5.5 are different, the two-dot chain line Z in Fig. 1O (B) should be used in advance. By changing the pitch of the magnetic poles of the rotor 3 in advance, the residual torque can be effectively and significantly reduced.

Furthermore, by arranging the plurality of young magnetic poles N and S of the rotor 3 at uneven pitches in the smooth direction, the θ-T characteristic can also be improved by the 13th
As shown in the figure, the characteristic curve has a thin waveform with a small slope near zero torque and small positive and negative torque values.

Therefore, torque fluctuations and speed fluctuations that occur during constant speed rotation, that is, when a constant pulse period is input, can be suppressed to extremely small values.

In the above explanation, the present invention was applied to a stepping motor, but the present invention is also applicable to a periodic motor driven by a two-phase sinusoidal current, or to a linear motor developed from the above-mentioned rotary motor. It can be similarly applied to near motors and the like.

The chevron shape of the stator balls 9 and 10 is not limited to a rectangular shape as shown in FIG. 11, but also a trapezoid as shown in FIG. 14 (A), a convex inflection as shown in FIG. 14 (13) Various shapes can be adopted, such as an airfoil shape or a shape with varying thickness as shown in FIG. 14(C).

〔effect〕

As is clear from the above description, according to the present invention, the fii
fl'! With this configuration, it is possible to control the residual torque, torque fluctuations, and speed fluctuations of the motor during constant speed rotation, and to obtain a rotary motor capable of stable gA motion.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of a PM type stepping motor suitable for applying the present invention, Fig. 2 is a partial perspective view of the scooter shown in Fig. 1, and Fig. 3 is a partial perspective view of the rotor shown in Fig. 1. A perspective view of
FIG. 4 is a circuit diagram showing the excitation phases of the stepping motor in FIG. 1, and FIGS. Figure 6 is a graph illustrating the angle-torque (θ-T) characteristics obtained by each phase excitation in Figures 5 (A) and (B), and Figure 7 (A) and (B) are graphs for 1-1 phase excitation. Graph illustrating the rotor speed and torque values when accelerating to a constant speed at , Figure 8 is a schematic development of the stator ball part and rotor magnetic pole part of a conventional stepping motor, and Figure 9 shows the indexing of the balls of a pair of stators. Graph 10th illustrating the residual torque of each stator when the pitch and the magnetic pole pitch of the rotor are arranged at equal pitches.
Figures (A) and (B) are graphs each illustrating the residual torque of the motor caused by the unbalance of the residual torque of a pair of stators. 12 is a graph illustrating the pitch (spacing) change 1j (characteristic) between the magnetic poles of the rotor in FIG. 11, and FIG. 13 is a graph showing the angle-torque (θ-T) characteristics of the motor in FIG. An illustrative graph,
Figures 14 (A) to (C) show the i of the stator ball, respectively.
'1) It is a schematic diagram illustrating a carved shape. 1----- Stator unit, 2-----
−−・−Output pin I, 3・−・−・−・・−Rotor,
5.5--11-stator, 8--coil, 9.10--stator ball, t
・−・・−・−Time, θ−・−・・−・−・Angle, ω・−・−・・・Rotor rotation speed, T...
・・・・・・・・・-Torque, X, Y・・−・−・−・−
Residual torque. Figure 5 (A) Chi 4 @ L-knee Figure 6 Figure 13 Figure 14 (G)

Claims (1)

[Claims] (1) A stator having a plurality of stator balls arranged in the circumferential direction and equipped with a coil wound around each stator ball to generate magnetic flux, and a plurality of stator balls arranged on the outer circumferential surface opposite to the inner circumferential surface of the stator. 1. A motor comprising a permanent magnet rotor having magnetic poles, characterized in that circumferential picks of each magnetic pole of the rotor are arranged at unequal pitches.