JP3037340B2 - Permanent magnet type 2-phase stepping motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a permanent magnet type two-phase stepping motor which is incorporated in various devices and used as a drive source for various operating parts.

<< Prior Art >> FIG. 2 shows a typical structure of a small stepping motor incorporated in various servo mechanisms. This is a permanent magnet type two-phase stepping motor, in which a rotor having a shaft 2 attached to the center of a multi-pole magnetized cylindrical magnet (rotor magnet) 1, an A-phase stator block 3a and a B-phase stator block 3b And a claw-pole type stator. As shown in FIG. 3, the rotor magnet 1 has S poles and N poles arranged at a constant pitch on the circumferential surface thereof.
The A-phase stator block 3a and the B-phase stator block 3b have the same configuration, and the magnetic pole teeth 4 arranged at a constant pitch on the inner peripheral surface.
, And an exciting coil 6 wound around the yoke 5
It is composed of However, the A-phase stator block 3a and the B-phase stator block 3b are positioned and integrated so that the arrangement of the magnetic pole teeth 4 has a phase difference of 90 ° in electrical angle.

Thus, in the two-phase stepping motor, the A-phase portion and the B-phase portion
The phase difference between the phase portions is set to be exactly 90 °, thereby obtaining a constant step angle.

<< Problems to be Solved by the Invention >> In this kind of permanent magnet type two-phase stepping motor, if the torque is relatively large, the settling time (attenuation from when the final pulse signal is input to the stepping motor until the rotor comes to a standstill). (Vibration time) is relatively large. That is, when the torque is large, the overshoot at the time of stopping the excitation becomes large, the amplitude of the damped vibration becomes large, and the settling time becomes long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to realize a permanent magnet type two-phase stepping motor having a large starting torque and a short settling time.

<< Means for Solving the Problems >> Therefore, the present invention is specified by the following items (1) to (4).

(1) A stepping motor comprising a permanent magnet rotor having a shaft attached to the center of a cylindrical permanent magnet, and an electromagnet stator disposed to face the peripheral surface of the permanent magnet rotor.

(2) The S pole and the N pole are arranged at a constant pitch on the peripheral surface of the permanent magnet.
A first phase magnetization arrangement in which the poles are arranged, and S
A second phase magnetized arrangement in which the poles and the N poles are arranged is formed in the axial direction.

(3) The first surface of the permanent magnet is provided on the peripheral surface of the stator.
A first-phase magnetic pole tooth array having a constant pitch facing the phase-magnetized array and a second phase magnetic pole tooth array having the constant pitch facing the second phase-magnetized array of the permanent magnets are formed in the axial direction. At the same time, an exciting coil is wound corresponding to each of the first phase magnetic pole tooth arrangement and the second magnetic pole tooth arrangement.

(4) the positional relationship between the first phase magnetized array and the first phase magnetic pole tooth array and the positional relationship between the second phase magnetized array and the second phase magnetic pole tooth array are relatively shifted; The shift amount is set to 90 ° ± α (5 ° <α <20 °) when expressed by an electrical phase angle.

<< Operation >> When the phase difference is set to 90 ° ± α (5 ° <α <20 °) as described above, the step angle of the motor is not constant, and the step angle becomes large, small, large, small for each step. And change. At the same time, the torque of the motor is not constant, and the torque changes to large, small, large, and small at each step. Therefore, if the motor is stopped at the step where the torque becomes small, the settling time is shortened, and the starting torque at the time of the next restart is increased.

<< Embodiment >> The structure of the permanent magnet type two-phase stepping motor shown in FIG. 2 is common to the embodiment of the present invention. In the structure shown in FIG. 2, the arrangement of the magnetic pole teeth 4 of the A-phase stator block 3a and the B-phase stator block 3b is set to a phase difference of 90 °, whereas the magnetization pattern of the rotor magnet 1 is changed to the first.
By forming as shown in the figure, the phase difference between the A-phase portion and the B-phase portion is set to 70 ° to 85 °.

The magnetization pattern of the rotor magnet 1 shown in FIG. 1 is divided into an A-phase portion 1a corresponding to the A-phase stator block 3a and a B-phase portion 1b corresponding to the B-phase stator block 3b, each of which has a constant pitch. The S and N poles are magnetized, and A
The arrangement of the magnetic poles of the phase portion 1a and the B phase portion 1b are not in phase,
A phase difference corresponding to α of 90 ° ± α is set. As a result, the A-phase stator block 3a and the B-phase stator block
The phase difference 90 ° of the magnetic pole teeth 4 of 3b and the phase difference α of the rotor magnet 1 side
The total phase difference between the A-phase portion and the B-phase portion is 90 ° ± α.

Thus, by eliminating the phase difference between the two phases from 90 °, the step angle changes to large, small, large, and small at each step, and at the same time, the torque changes to large, small, large, and small at each step. Change.

Note that the phase difference between the first phase portion and the second phase portion is determined by a combination of the phase difference on the rotor magnet side and the phase difference on the stator side.
As shown in the figure, the phase difference is zero, and the phase difference between the magnetic pole teeth 4 of the A-phase stator block 3a and the B-phase stator block 3b is calculated.
If the angle is set to 80 °, the phase difference between the A phase portion and the B phase portion becomes 80 °. As described above, there are various means for setting the phase difference to a predetermined value, and the present invention can be implemented by setting the phase difference by any method.

<< Effects of the Invention >> As described in detail above, in the permanent magnet type two-phase stepping motor according to the present invention, the step angle and the torque of the motor change from large to small, large to small, and small to small. If the motor is stopped at the step where the value becomes smaller, the settling time becomes relatively short. When the motor is restarted from that state, the motor starts from the step where the torque is large, and a large starting torque can be obtained.

[Brief description of the drawings]

FIG. 1 is a development view of a magnetized pattern of a rotor magnet according to one embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of a permanent magnet type two-phase stepping motor common to the embodiment of the present invention and a conventional one, FIG. 3 is a perspective view showing a general magnetization pattern of the rotor magnet. 1 rotor magnet 1a A-phase part, 1b B-phase part 2 rotor shaft 3a A-phase stator block 3b B-phase stator block 4 magnetic pole teeth 5 yoke 6 excitation coil

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 37/00-37/24 H02K 1/27 501 H02K 15/03

Claims (1)

(57) [Claims] 1. The invention specified by the following items (1) to (4). (1) A stepping motor comprising a permanent magnet rotor having a shaft attached to the center of a cylindrical permanent magnet, and an electromagnet stator disposed to face the peripheral surface of the permanent magnet rotor. (2) The S pole and the N pole are arranged at a constant pitch on the peripheral surface of the permanent magnet.
A first phase magnetization arrangement in which the poles are arranged, and S
A second phase magnetized arrangement in which the poles and the N poles are arranged is formed in the axial direction. (3) The first surface of the permanent magnet is provided on the peripheral surface of the stator.
A first-phase magnetic pole tooth array having a constant pitch facing the phase-magnetized array and a second phase magnetic pole tooth array having the constant pitch facing the second phase-magnetized array of the permanent magnets are formed in the axial direction. At the same time, an exciting coil is wound corresponding to each of the first phase magnetic pole tooth arrangement and the second magnetic pole tooth arrangement. (4) the positional relationship between the first phase magnetized array and the first phase magnetic pole tooth array and the positional relationship between the second phase magnetized array and the second phase magnetic pole tooth array are relatively shifted; The shift amount is set to 90 ° ± α (5 ° <α <20 °) when expressed by an electrical phase angle.