JPH0511784U - Stepping motor - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a stepping motor that can reduce loss torque, can be downsized, and can be constructed at low cost. [Structure] Rotor 1 in PM type stepping motor
The magnetic flux density of the rotor portion facing the portions other than the yoke pole tooth portions of the two sets of stator portions by adjusting or non-magnetizing one axial portion of one cylindrical permanent magnet 11a of 0a is illustrated. The surface magnetic flux distribution 12a is weakened. As a result, the loss torque in this portion can be reduced, and the torque characteristics and vibration characteristics can be improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lens driving device used for a video camera, a floppy disk head driving device, and various OA equipment driving devices.

[0002]

[Prior Art]

 In recent years, along with the trend toward lighter, thinner, shorter, and smaller devices, the drive stepping motors have also become smaller, and there is a demand for improved volumetric efficiency as a motor.

A conventional PM type stepping motor will be described below with reference to the drawings. FIG. 5 shows a conventional PM type stepping motor in which a ring-shaped coil 2 is wound around a first bobbin 1, the end surface of the bobbin is covered with a pair of yokes 3a and 3b, and the inner peripheral surface of the yoke is a comb. A stator composed of a first stator portion 5a in which tooth-shaped pole teeth are arranged and a second stator portion 5b formed in the same manner as the first stator portion are stacked and housed in the motor frame 6. The rotor 8 is provided with a single cylindrical permanent magnet 7 having a plurality of magnetized magnets on its outer circumference which faces the yoke pole teeth 4a and 4b inside the two sets of stators and is rotatable. is there.

FIG. 6 shows a surface magnetic flux distribution 9 in the axial direction of a rotor 8 equipped with one cylindrical permanent magnet 7 used in the conventional motor described above, which is uniform in the axial direction. It is magnetized.

In the above structure, the comb-teeth pole teeth of the yoke are excited by sequentially energizing the coils of each stator, and a plurality of magnetized opposing rotors are attracted or repelled to cause rotor rotation. Rotates.

[0006]

[Problems to be solved by the device]

 In such a conventional PM type stepping motor, the detent torque is increased without contributing to the generated torque due to the magnetic flux of the rotor opposite to the pole tooth part of the stator yoke, and the motor efficiency is deteriorated. Was there.

As another countermeasure against this, in another conventional example, there is a motor having a structure in which a cylindrical permanent magnet having a magnetized rotor is divided into two parts and a loss torque generating part is eliminated, but the cost is high in the structure, and the motor is expensive. There was a problem that it was difficult to miniaturize the magnet manufacturing.

The present invention solves the above problems, and an object thereof is to provide a small PM type stepping motor with reduced loss torque.

[0009]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention is one in which a rotor is composed of one cylindrical permanent magnet, and a part of the cylindrical permanent magnet in the axial direction is adjusted magnetized or non-magnetized.

[0010]

[Action]

 According to the present invention, the loss torque of the PM type stepping motor can be reduced by the configuration described above, and at the same time, the cost can be reduced because the configuration is simple.

[0011]

【Example】

 Hereinafter, a first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 10a denotes a PM type stepping motor rotor according to the present invention. The structure of the PM type stepping motor, which is the main body, is the same as the conventional one, and the description of the same parts as those of the conventional one will be omitted. A part of the cylindrical permanent magnet 11a in the rotor 10a in the axial direction is magnetized or non-magnetized, and the two parts other than the yoke pole tooth parts 4a and 4b of the two stator parts 5a and 5b shown in FIG. This is a configuration in which the axial surface magnetic flux distribution of the opposing rotors is weakened to form the axial surface magnetic flux distribution 12a as shown in FIG. As described above, according to the PM type stepping motor of the embodiment of the present invention, the rotor can be configured as one cylindrical permanent magnet at a low cost, and the rotors other than the two yoke pole tooth portions of the two stator portions can be provided. It is possible to reduce the loss torque generated by the magnetic flux of the rotor opposed to.

FIG. 2 shows a second embodiment of the present invention. In FIG. 2, 10b is a rotor of the present invention of a PM type stepping motor, and the structure of the PM type stepping motor, which is the main body, is the same as the conventional one. The rotor 10b is subjected to adjustment magnetization or non-magnetization in a part of the axial direction of the cylindrical permanent magnet 11b so that the axial surface magnetic flux distribution of the rotor faces the centers of the two stator portions. 2 is weakened in the front and back to form an axial surface magnetic flux distribution 12b as shown in FIG. As described above, according to the PM type stepping motor of the embodiment of the present invention, the rotor can be configured with one cylindrical permanent magnet at a low cost, the loss torque generated by the magnetic flux of the rotor can be reduced, and the rotor can be smoothed. You can get a nice rotation.

FIG. 3 shows a third embodiment of the present invention. In FIG. 3, 10c is a rotor of the present invention of a PM stepping motor, and the structure of the PM stepping motor, which is the main body, is the same as the conventional one. In the present embodiment, a part of the cylindrical permanent magnet 11c in the rotor 10c in the axial direction is subjected to adjustment magnetization or non-magnetization, and the axial magnetic flux distribution 12c of the rotor is taken into consideration in consideration of the total magnetic characteristics of the motor. 3, the center position of the non-magnetized part is displaced from the center positions of the two sets of stator parts as shown in FIG. As described above, according to the PM type stepping motor of the embodiment of the present invention, the rotor can be configured with one cylindrical permanent magnet at a low cost, and the loss torque generated by the magnetic flux of the rotor is shown in FIG. As shown in the characteristic diagram, it can be significantly reduced compared to the conventional specifications, and smooth rotation can be obtained.

[0015]

[Effect of the device]

 As is apparent from the above-described embodiments, according to the present invention, it is possible to provide a stepping motor that can reduce loss torque and that has excellent torque characteristics and vibration characteristics despite its inexpensive structure.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a rotor of a stepping motor according to a first embodiment of the present invention and its axial surface magnetic flux distribution.

FIG. 2 is the same plane sectional view of the second embodiment of the present invention.

FIG. 3 is the same plane sectional view of a third embodiment of the present invention.

FIG. 4 is a characteristic diagram of a third embodiment of the present invention.

FIG. 5 is a plan sectional view of a stepping motor.

FIG. 6 is a sectional plan view showing a rotor of a conventional stepping motor and a surface magnetic flux distribution in the axial direction thereof.

[Explanation of symbols]

 3a, 3b Yoke 4a, 4b Yoke pole tooth part 5a, 5b Stator part 7,11 Cylindrical permanent magnet 8,10 Rotor 9,12 Axial surface magnetic flux distribution

Claims (1)

[Claim 1] A ring-shaped coil is wound around a first bobbin, and the bobbin end surface is covered with a pair of yokes facing each other, and a comb-shaped pole is formed on the inner peripheral surface of the yoke. A stator composed of a first stator part in which teeth are arranged and a second stator part similar to the first stator part, and a cylindrical permanent magnet having a plurality of magnetized outer circumferences. In the PM type stepping motor formed with the rotor,
The rotor is composed of one cylindrical permanent magnet, and a part of the cylindrical permanent magnet in the axial direction is adjusted and magnetized or non-magnetized.