JP2599082B2 - 4-phase stepping motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid type four-phase stepping motor, and more particularly, to a detent torque (detent torque).
The present invention relates to a four-phase stepping motor in which tent torque is reduced and driving torque is increased.

[0002] Here, the detent torque is a torque for maintaining a fixed position even when the motor is not excited. When a current is applied to the motor, a specific phase (single or plural) is excited. This is essentially different from the static torque that appears when the vehicle is moving, that is, the static torque that is indicated by the stiffness characteristic.

[0003]

2. Description of the Related Art Conventionally, this kind of four-phase stepping motor
Is a cross section showing the mutual relationship between the stator and the rotor in FIG.
Some are shown in the figure. In FIG.
Salient poles 1₁, 1_Two, 1_Three, ............ 1₇, 1 ₈But
And each salient pole 1₁, 1_Two, ………
1₈4 or 5 on the surface facing the rotor 2
Stator teeth 3 have equal pitch τ_SAre arranged in
An even number of rotor teeth 4 on the outer circumference of the trochanter 2 side have the same pitch τ.
_RIt is arranged in. Reference numeral 5 in FIG.
Two salient poles 1 facing each other₁, 1_Five1 _Two, 1₆;
1_Three, 1₇1_Four, 1₈With a heteropolar winding
Thus, each phase is constituted. 6 is the output of the rotor 2
Axis.

A permanent magnet magnetized in an axial direction (not shown) is incorporated in the rotor 2 and comprises two iron cores each having the even number of rotor small teeth 4 on the outer periphery thereof.
One core is magnetized to the N pole and the other core is magnetized to the S pole, and the small teeth 4 and 4 are shifted by a half pitch (electrically 180 °). FIG. 2 shows one of them.

[0005]

[SUMMARY OF THE INVENTION However, in such a conventional 4-phase stepping motor, each salient pole 1 _1, 1 _2, 1 _3, of ......... 1 _8, the stator teeth 3
There are four salient poles and five salient poles, which are magnetically unbalanced as a whole, so that the detent torque is large and the drive torque that should be generated is sufficient. There was a problem that it could not be done.

[0006] That is, according to FIG. 2, two salient poles 1 ₁ constituting the respective phases, 1 _5; 1 _2, 1 _6; facing the ...... arranged, the more different polarities this due to the excited such, the salient poles 1 ₁ of the 2 solid, 1 _5; 1 _2, 1 _6; ... the same phase from the need to balance the shape number of the small teeth 3,
It is composed of four salient poles and five salient poles.
Also, since there are portions where the number of small teeth 3 is adjacent to four salient poles and five salient poles are adjacent to each other, the magnetic balance of the entire motor is broken.

Thus, each salient pole 1₁, 1_Two, ………
1₈Detent torque T generated by _D1, T_D2, ... T_D8
Will have different sizes and shapes. Therefore, external
Low-order components in the detent torque
In addition, its amplitude is large. Also, originally
The drive torque to be performed was not sufficiently obtained.

[0008] The present invention has been made in view of such a point,
An object of the present invention is to provide a four-phase stepping motor that solves the above-mentioned problems and achieves a magnetic balance from the overall structure of the stepping motor, and reduces the detent torque and increases the driving torque.

[0009]

According to a first aspect of the present invention, a stator having eight salient poles is provided.
In a hybrid type four-phase stepping motor including a rotor having an even number of small teeth arranged at an equal pitch on the outer periphery, five or more stator small teeth equal to each of the salient poles are provided. A phase is formed by two adjacent salient poles, and the two salient poles are excited to have different polarities to reduce detent torque and increase driving torque. I do.

[0010]

Since the present invention is constructed as described above, the magnetic balance is improved from the overall structure of the stepping motor, the detent torque is reduced, and the stator teeth of each salient pole of the stator are reduced. Can be increased as a whole without reducing the number of conventional stepping motors.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing the mutual relationship between a stator and a rotor showing an embodiment of a four-phase stepping motor according to the present invention. The same members as those in FIG.

In the figure, five stator small teeth 3 are provided on the surface of the stator 1 facing the rotor 2 of the _eight salient poles 1 ₁ , 1 ₂ ,. Arranged in _S.

Each of the salient poles 1₁, 1_Two, ............ 1
₈Two adjacent salient poles 1₁, 1_Two1_Three, 1_Four;
1_Five, 1₆1₇, 1₈The stator to constitute one phase
The windings 5 and 5 are connected, and the two
Salient pole 1₁, 1_Two1_Three, 1_Four1 _Five, 1₆1₇, 1₈
Are excited so as to have mutually different polarities.

At the same time, the two salient poles 1 ₁ , 1 ₂ ;
1 _3, 1 _4; 1 _5, 1 _6; by 1 _7, 1 ₈ to the configuration described above, respective salient poles ₁ 1, 1 _2, the stator number of teeth 3 ......... 1 ₈ An equal number, for example, five, can be provided without reduction.

By the way, the detent torque of the hybrid type stepping motor is a holding torque generated when the winding 5 is not energized, and the stator 1 and the rotor 2 have a magnetic force between the small teeth 3 and 4 facing each other. It is generated by the attractive force. This attraction force is generated by a magnetic flux from the permanent magnet incorporated in the rotor 2 and passing between the opposed small teeth 3 and 4.

Each salient pole 1 of the stator 1₁, 1_Two, ............ 1₈
This detent torque T _Di(I = 1-8)
Is the pitch τ of the rotor small teeth 4_RPeriodically
And the shape for the size and angular displacement is the salient pole
1₁, 1_Two, ............ 1₈Pitch τ of stator teeth 3_S,
It is determined by the shape, the number, and the amount of the passing magnetic flux.

However, the detent torque observed from the output shaft 6 of the stepping motor depends on the salient poles 1 ₁ ,
1 _2, since the sum of the detent torque T _Di of each ......... 1 _8, harmonic components of the 7th or less than overlay is erased, the little ones as the amplitude.

FIG. 2 is a graph showing detent torque characteristics with respect to a rotor angle of a four-phase stepping motor showing test results of the present embodiment. In comparison with the conventional example shown by a dotted line, the detent torque of the present embodiment shown by a solid line is It can be seen that it is considerably reduced and improved.

[0019] In the stator 1, as described above, the two salient poles ₁ 1, which constitutes one phase, 1 _2; 1 _3, 1 _4; 1 _5,
1 _6; 1 _7, by 1 ₈ disposed adjacent each said salient poles 1 _1, 1 _2, as all five without reducing the number of stator teeth 3 of ......... 1 _8, detent While reducing the torque, the two salient poles 1 ₁ ,
1 ₂ ; 1 ₃ , 1 ₄ ; 1 ₅ , 1 ₆ ; 1 ₇ , 1 ₈ By effectively utilizing the main magnetic flux and increasing the number of stator small teeth 3 as a whole, the overall driving torque can be reduced. Is increasing.

The technique of the present invention is not limited to the technique in the above-described embodiment, but may be implemented by means of another embodiment having the same function. Can be changed or added.

[0021]

As is clear from the above description, according to the four-phase stepping motor of the present invention, five or more stator small teeth equal to each salient pole of the stator are provided, and two adjacent small teeth are arranged.
Since the two salient poles constitute one phase and the two salient poles are excited so as to have different polarities, a magnetic balance can be obtained, the detent torque of the stepping motor can be reduced, and the stator , The number of stator small teeth of each salient pole is increased as a whole, whereby the driving torque of the motor can be increased. For this reason, a four-phase stepping motor that can obtain smooth rotation and is also suitable for microstepping can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a mutual relationship between a stator and a rotor showing one embodiment of a four-phase stepping motor of the present invention.

FIG. 2 is a graph showing detent torque characteristics with respect to a rotor angle showing test results of the present embodiment.

FIG. 3 is a cross-sectional view illustrating a mutual relationship between a stator and a rotor of a conventional four-phase stepping motor.

[Explanation of symbols]

1 Stator 1 ₁ , 1 ₂ , 1 ₃ , ... 1 ₈ Salient pole 2 Rotor 3 Stator small tooth 4 Rotor small tooth 5 Stator winding 6 Output shaft τ _R Rotor small tooth pitch τ _S fixed Child tooth pitch

Claims (1)

(57) [Claims] 1. A hybrid four-phase stepping motor comprising a stator having eight salient poles disposed thereon and a rotor having an even number of small teeth disposed at an equal pitch on an outer periphery thereof. At least five stator teeth, each equal to one of the poles, are arranged, two adjacent salient poles constitute one phase, and the two salient poles are excited to have different polarities. And reducing the detent torque and increasing the driving torque.