JPS6331455A - Motor - Google Patents

Abstract

PURPOSE:To reduce variations in torque and speed of a motor by unequally setting the circumferential pitch of the stator poles 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 is secured to the unit 1. The unit 1 is formed by bonding two stators 5 disposed adjacently in the direction of the shaft 2, and 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, a plurality of poles of the rotor 3 are disposed at an equal interval (equal pitch) in the circumferential direction, and stators 5 are arranged 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 poles forming a magnetic path and a permanent magnet rotor.

[Prior art] This type of motor includes stepping motors, synchronous motors, etc. In the case of stepping motors, pole teeth (stator poles) of a stake have multiple excitation phases (excitation coils).
and [Ii of the rotor, and by manually applying pulses to each excitation phase in a fixed order, the rotor is rotated by a fixed angle in a predetermined direction.

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

Moreover, this stepping motor has multiple poles I! excited by the coil! It consists of a rotor with multiple magnetic poles supported in a stator with i (stator poles), and can be roughly divided into VR with salient poles on the circumferential surface of the rotor.
(variable reluctance) type, P uses a permanent magnet in the rotor
It can be classified into M (permanent magnet) type, and hybrid PM type which is a combination of VR type and PM type.
The present invention is particularly applicable to PM type stepping motors.

The PN2 type stepping motor has a stator having a plurality of stator poles (stake pole teeth) arranged in the circumferential direction and a coil wound around each stator pole 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 a constant pulse period input, each excitation phase is sequentially switched in the positive torque range to accelerate and then -constant In the pulse period input region, the switching torque integral value is set to zero to create a constant speed drive state so as to balance the positive and negative torques of the excitation phases.

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 type, the circumferential pitch of the stator poles and the circumferential pitch of the magnetic poles of the rotor are both set to the same pitch, and based on their positional relationship, the angle-torque characteristic (θ-T Since the characteristic (characteristic) is a repeating approximately sinusoidal waveform, the slope of the torque curve near the torque zero point is large, and the speed fluctuations caused by positive and negative torques are large.

Furthermore, since the rotor's magnetized magnetic pole pitch and the stator pole tooth pitch are the same for all phases, many magnetized magnetic poles and stator poles always occupy positions facing each other, resulting in residual torque (cogging). torque or detent torque) tended to be extremely large.

Therefore, in conventional motors, large speed fluctuations near the torque zero point and the presence of large residual torque prevent smooth rotation, leading to problems such as unstable load motion and noise generation. was there.

〔the purpose〕

An object of the present invention is to provide a motor that can solve the problems of the prior art and operates stably and smoothly by reducing residual torque of the motor and reducing torque fluctuations and speed fluctuations during constant speed rotation. It is to be.

[Means to achieve the purpose]

The present invention provides a stator having a plurality of stake poles arranged in the circumferential direction and a coil wound around each stator pole to generate magnetic flux, and an outer circumferential surface facing the inner circumferential surface of the stator. In a motor comprising a permanent magnet type rotor having a plurality of magnetic poles, the above object is achieved by making the circumferential pitch of the stake poles disposed on the stator uneven.

〔Example〕

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

FIG. 1 shows a PM type stepping motor suitable for applying the present invention, FIG. 2 shows the outer stator in FIG. 1, and FIG. 3 shows the rotor in FIG. 1.

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 fixed to one end of the stator unit 1. .

The stator unit 1 has a divided structure in which two stakes 5.5 which are arranged adjacent to each other in the direction of the output shaft 2 are joined together. 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 poles 9 that protrude in the axial direction are formed at predetermined intervals in the circumferential direction, and the inner circumferential portion of the inner stator 7 has unevenness facing each of the outer stator poles 9 with a predetermined gap. A plurality of inner stake 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 poles 9.10 and attached to each stake pole 9.10 so as to generate magnetic flux 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 circles in the opening direction, as shown in FIG. Poles (N pole, S pole) N and S are arranged.

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

Note that each stator 5.5 can be formed by, for example, iA slope press forming, deep drawing, or the like.

In order to drive the upper EPM type stepping motor one after another at 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 driving transistors of each phase.

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.

Figures 5(A) 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 characteristics (θ-T characteristics) generated by the 1-1 phase excitation and the 2-2 +U excitation.

In Fig. 6, symbols I, ■, ■, and ■ indicate the θ-T characteristics of 1-1 phase excitation in which only the first, second, third, and fourth winding coils are excited, respectively. , and III indicates the θ-T characteristic of 2-2 phase excitation in which the first phase winding coil and the second phase winding coil are excited simultaneously.

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

In addition, in the graph of FIG. 6, for 2-2 phase excitation, I
Only the θ-T characteristics of n 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 1=0, tl, t
2, by sequentially switching from phase ■ - phase ■ - 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 stepping motor, the seventh
As is clear from the diagrams (A) and (B), even though it is called constant speed, the actual switching timing is t3, L4-------
... A slight speed fluctuation dω occurs.

However, in the conventional PM type stenobing momo,
As shown in the developed schematic diagram of FIG. 8, the stator poles 9.10 of the stator 5.5 are arranged at equal pitches in the circumferential direction, and the magnetic poles N 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 speed fluctuations caused by positive and negative torque fluctuations. was also a large value.

Furthermore, as is clear from the developed schematic diagram of the stator pole portion and rotor portion in FIG. 8, the stator pole 9.1o
Since the tooth pitch of the rotor 3 and the magnetizing hand box pitch of the rotor 3 are the same for all phases, many magnetized magnetic poles and stake balls always occupy positions facing each other, and the residual There was a supine position in which the cogging torque or detent torque was extremely large.

Riddle 3: By providing a pair of stakes 5.5 as shown in Figures 1 and 8, and selecting the phase and amplitude of the residual torque of each stake to be symmetrical in positive and negative, the residual torque of the motor can be reduced to zero. However, in reality, it is difficult to reduce the residual torque simply by providing a pair of stators 5.5, which is obvious from the mechanism of residual torque generation described below.

First, when the magnetization pitch of the rotor 3 and the indexing angle of the stator 5.5 are arranged at equal pitches as shown in Fig. 8, the residual torque at each stake 5.5 is as shown by curves A and B in the ninth plane. 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 are configured completely uniformly, the residual torque A is the sum of the residual torque B generated from
and residual torque B cancel each other out, and the residual torque appearing in the entire motor should become zero.

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(A) shows the case where the phases of the residual torques A and B of both stakes 5.5 are the same, and FIG.
B) shows a case where the amplitudes and phases of the residual torques A and 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 caused load operation to become unstable and noise to be generated.

FIG. 11 is an exploded side view of the stator pole section and rotor section of the P-cho type swamping motor according to the present invention.

FIG. 11 shows a stator unit 1 as shown in FIG. 1 in which two stators 5 having a structure in which a plurality of outer stator poles 9 and inner stator poles 10 are opposed to each other in an ffi state are arranged in the axial direction. 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. .5
are arranged at irregular intervals (unequal pitch) in the circumferential direction.

The unequal pitch arrangement of the stake balls 9.10 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 isomarginal manner. An arrangement that varies in size is adopted.

FIG. 12 shows the stator pole in the outer stator 6 or inner stator 7 of the stator 5 and the (n-1)th magnetized VA.
The change characteristics of the distance n1 between the poles will be illustrated.

As explained above, by arranging the stator poles 9.10 of the stator 5.5 at unequal pitches in the circumferential direction, even within the same phase, the magnetized magnetic poles N and S of the rotor 3 are opposed to each other. and the number of pairs of stake balls 9.10 can be significantly reduced, and the residual torque of the entire motor
(Cogging torque) was also able to be significantly reduced.

For example, if residual torques X and Y are generated due to the unbalance of the pair of stators 5.5 or the magnetization error of the rotor 3 shown in Fig. 10 (A) and (B), various errors may be generated. By taking this into account and shifting the circumferential pitch (phase) of the stator poles 9 and 10 in advance, it was possible to reduce the residual torque of the entire motor more effectively, such as to zero or to significantly reduce it.

That is, the residual torque can be effectively reduced by setting the pitch of the stake balls 9.10 in accordance with the dimensions of the stator 5.5 and the rotor 3 and the pattern of assembly errors.

For example, when the amplitude and phase of the residual torques A and B of both stakes 5.5 are different as shown in FIG. 10(B), If the pre-stator poles are changed by 9.10 degrees, the residual torque can be effectively and significantly reduced.

In addition, by arranging the stator poles 9 and 10 at uneven pitches in the circumferential direction, the θ-T characteristic has a small slope near zero torque and small positive and negative torque values, as shown in Figure 13. It becomes a characteristic curve of the waveform.

Therefore, torque fluctuations and speed fluctuations that occur during constant speed rotation, that is, during constant pulse rotation and high force, can be suppressed to extremely small values.

In the above explanation, the case where the present invention is applied to a stevening motor has been exemplified, but the present invention can also be applied to a periodic motor driven by a two-phase sinusoidal current, or a linear motor developed from the above-mentioned rotary motor. It can be similarly applied to near motors, etc.

Furthermore, the tooth shape of the stator poles 9 and 10 is not only rectangular as shown in FIG. 11, but also trapezoidal as shown in FIG. 14(A), convex inflection as shown in FIG. 14(B), etc. airfoil,
Furthermore, various shapes can be adopted, such as a shape in which the thickness is changed as shown in FIG. 14(C).

〔effect〕

As is clear from the above description, according to the present invention, the residual torque of the motor when rotating at a constant speed is reduced by 1-
A rotary motor that can control torque fluctuations and speed fluctuations and that can be driven stably can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a PM type steel stamping motor suitable for applying the present invention, FIG. 2 is a partial perspective view of the starter in FIG. 1, and FIG. 3 is a partial perspective view of the rotor in FIG. 1. A perspective view of
FIG. 4 is a circuit diagram showing the excitation phase of the stevening moke in FIG. 1, FIGS. 5(A) and (B) are timing charts of drive command signals for 2-2 phase excitation and 1-1 phase excitation, respectively; Figure 6 is a graph illustrating the angle-torque (θ-T) characteristics obtained by excitation of each phase in Figures 5 (A) and (B), and Figures 7 (A) and (B) are 1-1 phase graphs. A graph illustrating the rotor speed and torque values when accelerating to a constant speed during excitation, Fig. 8 is a schematic diagram of the development of the stator pole part and rotor magnetic pole part of a conventional stethoping moke, and Fig. 9 is a diagram of a pair of stators. 10th graph illustrating the residual torque of each stator when the ball indexing pitch and the rotor magnetic pole pitch 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, and Figure 11 is a schematic diagram of the development of the stator pole portion and rotor magnetic pole portion of the motor according to the present invention. Figure, 1st
2 is a graph illustrating the pitch (spacing) change characteristics of the stator poles in FIG. 11, FIG. 13 is a graph illustrating the angle-torque (θ-T) characteristics of the motor in FIG. 11, and FIG.
Figures (A) to (C) are schematic diagrams each illustrating the tooth shape of the stator pole. 1------ Stator unit, 2------- Output shaft, 3--------- Rotor, 5, 5--
---・Stake, 8-・-・・--Coil, 9.10
・・−・−・−・−Stake ball, −・−・−・Time, θ−−−−−−・−・・−Angle, ω−−− Rotor rotation speed, T=−・−1− --Torque, X, Y--
---Residual torque. Agent Patent Attorney Yasushi Ooto 3rd Ward Figure 4 Figure 5 (A) Kaya 4 @ -guchi-1-nee Figure 6 Figure 11

Claims (1)

[Claims] (1) A stator that has a plurality of stator poles arranged in the circumferential direction and a coil wound around each stator pole to generate magnetic flux, and a plurality of stator poles 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 the circumferential pitches of stator poles arranged on the stator are unequal pitches.