JP2006288066A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a small stepping motor which can be processed and assembled easily and producing a large output torque. <P>SOLUTION: The stepping motor comprises a rotor 13 having a permanent magnet 12 magnetized with multi-poles in the thrust direction and secured to a rotating shaft 11, an output shaft 14 being transmitted with rotation of a rotating shaft 11 while being decelerated through a deceleration means, bearings 15 and 16 for supporting the rotor 13 and the output shaft 14 rotatably, a housing 17 for securing the bearings 15 and 16 while keeping at predetermined positions and formed to surround the rotor, and stators 18 and 19 having a pair of U-shaped cores arranged on one magnetic pole area and wound with a coil and fixed to the bearings 15 and 16 to be inserted with the permanent magnet 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a stepping motor.

The configuration of a conventional stepping motor is shown in FIG.
FIG. 6 is a perspective view of a conventional claw pole PM type stepping motor with a part broken away.

  The stepping motor 50 includes a permanent magnet 54, an A-phase stack 51, and a B-phase stack 52. The permanent magnet 54 is composed of a plurality of magnetic bodies 53 in which N poles and S poles are alternately arranged outward in the radial direction of the rotor.

  The A-phase stack 51 is composed of an upper pole 51a, a lower pole 51b, and a coil 51c. Similarly, the B-phase stack 52 is formed of an upper pole, a lower pole 52b, and a coil 52c which are not shown. The A-phase stack and the B-phase stack are arranged with a ¼ pole pitch shifted.

  In the stepping motor configured as described above, the winding length of the coil is longer than the number of turns. Along with this, the resistance of the coil increases and the flowing current decreases. Moreover, since a coil is arrange | positioned on the outer side of a permanent magnet, a radius will become large with respect to the number of turns. In reducing the size, the number of turns decreases as the radius decreases. Since the magnetomotive force of the coil is expressed by the product of the current flowing through the coil and the number of turns, if the size is reduced, a sufficient magnetomotive force cannot be obtained and the output is also reduced.

  In addition, the A-phase stack 51 and the B-phase stack 52 are formed by a sheet metal press, but a complicated mold is required to form a complicated pole shape.

  Patent Document 1 discloses a description of a conventional stepping motor and an example of a stepping motor in which the radial direction is further reduced.

  Non-Patent Document 1 discloses various types of stepping motors.

JP 2002-34227 A Naoshi Mijo, Atsushi Sugawara “Stepping Motor and Microcomputer Control” General Electronic Publishing 2000 3rd Edition

  In the conventional stepping motor, since the coil is concentrically arranged with respect to the rotation axis outside the permanent magnet, the length of the coil becomes longer with respect to the number of turns. Accordingly, the resistance of the coil increases, the current does not flow easily, and a sufficient magnetomotive force cannot be obtained when the size is reduced.

  Further, in order to obtain a large output torque, a reduction gear is generally attached to the outside of the motor, and the size is increased accordingly.

  In addition, a complicated mold is required to form each stack.

  An object of the present invention is to provide a stepping motor that is small in size, high in output, and easy to assemble and assemble.

At least a rotor in which a permanent magnet magnetized in the direction of the rotation axis is fixed to the rotation axis;
An output shaft to which the rotation of the rotation shaft is decelerated and transmitted by the deceleration means;
A bearing for supporting the rotor and the output shaft;
A housing formed to hold the bearing in place and to surround the rotor;
The stepping motor includes a stator in which a coil is wound around a pair of U-shaped cores sandwiched between the permanent magnets and disposed on one magnetic pole area of the permanent magnet.

  In the stepping motor of the present invention, since the coil length can be reduced with respect to the number of turns by winding the coil around the core, the resistance value is reduced. Therefore, the magnitude of the current that can be flowed can be increased, and a large magnetomotive force can be obtained. Since the core is U-shaped, it can be formed without using a complicated mold.

  Further, by arranging the pair of stators on one magnetic pole area, the magnetic flux generated by the magnetomotive force generated by the coil is concentrated on one magnetic pole area, and the leakage magnetic flux is reduced. Furthermore, since the magnetic flux concentrates on the above-described convex portion at the front end of the stator, the generated magnetic flux is more efficiently converted into a rotational force.

  Further, only a pair of stators are driven, and the number of components is reduced. A reduction in the number of stators generally tends to reduce the torque as rotational output. However, a reduction means is provided inside the stepping motor to compensate for the decrease in output, and it is compact and has a high output stepping motor. Is obtained. In addition, processing and assembly are facilitated.

1 is an exploded perspective view showing an embodiment of the stepping motor of the present invention, FIG. 2 is a perspective view showing an embodiment of the stepping motor of the present invention, and FIG. 3 is a top view showing an embodiment of the stepping motor of the present invention. 4 and 4 are front cross-sectional views cut along AA shown in FIG.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the stepping motor 10 will be described.
The rotating shaft 11 is formed with a spherical portion 11a whose one side is processed into a hemispherical shape. Further, there are formed a gear portion 11b that also serves as a flange for fixing the permanent magnet 12 to be described later while maintaining a predetermined position, and an end surface portion 11c that positions the thrust direction with a predetermined gap. The material is a non-magnetic material (SUS303).

  The cylindrical permanent magnet 12 has a hole 12a formed in the central axis and is magnetized with four poles at equal angular intervals in the thrust direction. The number of magnetization is not limited to 4 poles, and may be increased within a possible range of magnetization. The material is a rare earth magnet (for example, neodymium).

  The shaft on the spherical surface portion 11a side of the rotating shaft 11 is inserted into the hole 12a of the permanent magnet 12, and abuts against the gear portion 11b which also serves as a flange, thereby positioning in the thrust direction. In the case of a bonded magnet, the fixation is slightly smaller than the shaft diameter of the rotary shaft 11 engaged with the hole 12a and lightly press-fitted and then fixed by adhesion. In the case of a sintered magnet, since it is easy to break, the diameter of the hole 12a is formed to be slightly larger than that of the rotating shaft 11, and after being positioned in the radial direction with a jig or the like, it is bonded and fixed. A permanent magnet 12 is attached to the rotating shaft 11 to form a rotor 13.

  The output shaft 14 is formed with spherical portions 14a and 14b whose both end portions are processed into a hemispherical shape. A gear portion 14c that meshes with the gear portion 11b of the rotary shaft 11 and an end face portion 14d that positions the thrust direction with a predetermined gap are provided.

  The rotor 13 and the output shaft 14 are supported by bearings 15 and 16 that support a thrust direction and a radial direction. The two bearings 15 and 16 are positioned by the housing 17 at predetermined positions in the thrust direction and the radial direction. The bearing 15 is provided with two slits 15a and 15b. The slits 15a and 15b are formed in a substantially C shape and make a pair. The bearing recess 15c includes an end surface portion 15d that supports the rotor 13 in the thrust direction and a side surface portion 15e that supports the rotor 13 in the radial direction (FIG. 4). The bearing recess 15f includes an end surface portion 15g that supports the output shaft 14 in the thrust direction and a side surface portion 15h that supports the output shaft 14 in the radial direction (FIG. 4). A radial direction positioning portion 15i and a thrust direction positioning flange portion 15j are provided so as to maintain a predetermined position with a housing 17 described later.

  The bearing 16 is provided with slits 16 a and 16 b at the same angular position as the bearing 15. The slits 16a and 16b are formed in a substantially C shape and make a pair. The bearing portion 16c includes an end surface portion 16d that supports the rotor 13 in the thrust direction and a through hole 16e that supports the rotor 13 in the radial direction (FIG. 4). The bearing portion 16f includes an end surface portion 16g that supports the output shaft 14 in the thrust direction and a through hole 16h that supports the output shaft 14 in the radial direction (FIG. 4). A radial direction positioning portion 16i and a thrust direction positioning flange portion 16j are provided so as to maintain a predetermined position with the housing 17. The bearings 15 and 16 are made of non-magnetic bearing material (brass or resin).

  The housing 17 has an oval shape in which two hollow cylinders are coupled, and rectangular notches 17a and 17b are provided at positions corresponding to the slits formed in the bearings 15 and 16 on both end surfaces. . A stator, which will be described later, is inserted into and fixed to the notches 17a and 17b of the housing 17 and the slits of the bearings 15 and 16. The rotor 13 and the output shaft 14 are housed inside the housing 17 and are protected from the outside. The inner shape of the oval cylinder is formed so as to fit the outer shape of the radial direction positioning portions 15i and 16i of the bearing. The material is a non-magnetic material (aluminum).

  The stator 18 is formed by winding a coil 18b around a core 18a. A soft magnetic material is generally used for the core material (for example, permalloy, pure iron). In order to bring out a predetermined performance, a post-processing heat treatment is performed.

  In general, a coil wound around a bobbin is generally attached to a core. However, in order to further reduce the size, the coil is wound without using a bobbin in the embodiment of the present invention. If a coil is wound directly around the core, there is a possibility that disconnection or a short circuit due to disconnection may occur. To prevent this, a thin insulating tape is wound around the core, or a coil is wound after varnish is applied. Similarly, the stator 19 is formed by winding a coil 19b around a core 19a.

Next, the assembly procedure will be described.
The radial direction positioning portion 15i of the bearing 15 is inserted into the housing 17 so that the slit directions coincide with each other, and the thrust direction positioning flange portion 15j is abutted and fixed. Fixing uses an adhesive.

  The spherical portion 11a of the rotor 13 is inserted into the bearing recess 15c. The spherical portion 14a of the output shaft 14 is inserted into the bearing recess 15f. At this point, the gear portion 11b of the rotor 13 and the gear portion 14c of the output shaft 14 are engaged.

  Next, the direction of the slits of the bearing 16 and the housing 17 is made to coincide with each other, the through hole 16c of the bearing 16 is formed on the opposite end surface side of the spherical portion 11a of the rotor 13, and the through hole of the bearing 16 is formed on the spherical portion 14b of the output shaft 14. While inserting 16f, the radial direction positioning portion 16i of the bearing 16 is inserted into the housing 17, and the thrust direction positioning flange portion 16j is abutted and fixed. Fixing uses an adhesive.

  The thrust direction of the rotating shaft 11 is regulated with a predetermined clearance between the spherical surface portion 11a and the end surface portion 11c of the rotating shaft 11 and the end surface portions 15d and 16d of the bearings 15 and 16.

  The thrust direction of the output shaft 14 is regulated with a predetermined clearance between the spherical surface portion 14a and the end surface portion 14d of the output shaft 14 and the end surface portions 15g and 16g of the bearings 15 and 16.

  The rotor 13 and the output shaft 14 are pivotally supported by the bearings 15 and 16 and the housing 17.

  Next, the stator is inserted and fixed in a slit formed in the bearing. The stator 18 is inserted into the slits 15a and 16a until they abut against each other. Similarly, the stator 19 is inserted into the slits 15b and 16b until it abuts. Thereby, positioning in the radial direction is performed. Since the slits 15a (16a) and 15b (16b) are arranged on one magnetic pole area (1/4 circle) so as to sandwich the permanent magnet, the stator 18 and the stator 19 which are inserted into the slit and fixed. Are arranged on one magnetic pole area. With this configuration, magnetic flux leakage is reduced, and magnetic force is efficiently converted into output torque. The thrust direction is positioned using a jig (not shown) and fixed with a predetermined gap from the permanent magnet. Fixing uses an adhesive.

  The wiring is performed so that the stator 18 is in the A phase and the stator 19 is in the B phase. Therefore, a voltage can be individually applied to each stator.

Subsequently, the operation will be described.
In small stepping motors, excitation methods such as two-phase excitation and 1-2 phase excitation are common. The embodiments of the present invention can also be rotated by these excitation methods. Here, description will be made taking two-phase excitation as an example. FIG. 5 is a view showing the principle of rotation of the stepping motor according to the present invention as viewed from the bearing 16 side, and is a view for explaining clockwise rotation. The S pole is displayed in black for easy understanding. Further, the circles on the permanent magnet 12 in the figure are shown for the purpose of recognizing the rotational position for the sake of explanation.

  First, all the stators are excited to the S pole. Then, the permanent magnet 12 stops at the position shown in FIG. ((1))

  Next, the magnetic pole of the stator 19 is reversed and excited to the N pole. Then, a clockwise rotational moment is generated in the permanent magnet 12 by the generated magnetic force, and the permanent magnet 12 rotates 45 degrees clockwise and stops. ((2))

Next, the magnetic pole of the stator 18 is reversed and excited to the N pole. Due to the generated magnetic force, a clockwise rotational moment is generated in the permanent magnet 12, and the permanent magnet 12 rotates 45 ° clockwise and stops. ((3))

  Next, the magnetic pole of the stator 19 is reversed and excited to the S pole. Then, a clockwise rotational moment is generated in the permanent magnet 12 by the generated magnetic force, and the permanent magnet 12 rotates 45 degrees clockwise and stops. ((4))

Next, the magnetic pole of the stator 18 is reversed and excited to the S pole. Due to the generated magnetic force, a clockwise rotational moment is generated in the permanent magnet 12, and the permanent magnet 12 rotates 45 ° clockwise and stops. ((5))
Here, the rotor 13 rotates 180 °. If changing the magnetic pole is one step, one rotation is made in eight steps. Needless to say, when rotating in the counterclockwise direction, the order in which the magnetic poles are reversed may be reversed.

  The rotation generated in the rotor 13 is transmitted from the gear portion 11b to the gear portion 14c of the output shaft 14. The gear is decelerated at the ratio of the number of teeth and is rotated from the output shaft 14. Accordingly, the rotational speed is reduced by the ratio of the number of teeth, and the torque is increased by the ratio of the number of teeth.

1 is an exploded perspective view showing an embodiment of a stepping motor of the present invention. The perspective view which shows one Example of the stepping motor of this invention The top view which shows one Example of the stepping motor of this invention Front sectional view cut along A-A shown in FIG. FIG. 5 is a diagram illustrating the rotation of the stepping motor according to the present invention viewed from the bearing 16 side and illustrating the clockwise rotation. The perspective view which fractured | ruptured and showed one part with the conventional claw pole type PM type stepping motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stepping motor 11 Rotating shaft 11a Spherical surface part 11b Gear part 11c which served as a flange End surface part 12 Permanent magnet 12a Hole 13 Rotor 14 Output shaft 14a Spherical part 14b Spherical part 14c Gear part 14d End surface part 15 Bearing 15a Slit 15b Slit 15c Bearing concave part 15d End surface portion 15e Side surface portion 15f Bearing concave portion 15g End surface portion 15h Side surface portion 15i Radial direction positioning portion 15j Thrust direction positioning flange portion 16 Bearing 16a Slit 16b Slit 16c Bearing portion 16d End surface portion 16e Through hole 16f Bearing portion 16g End surface portion 16h Through hole 16i Radial direction positioning portion 16j Thrust direction positioning flange portion 17 Housing 17a Notch portion 17b Notch portion 18 Stator 18a Core 18b Coil 19 Stator 19a Core 19b Coil 50 Ppingumota 51 A Phase stack 51a upper pole 51b lower pole 51c coil 52 B phase stack 52b lower pole 52c coil 53 a plurality of magnetic bodies 54 a permanent magnet

Claims (1)

at least,
A rotor in which a multi-pole magnetized permanent magnet is fixed to the rotation axis;
An output shaft to which the rotation of the rotation shaft is decelerated and transmitted by the deceleration means;
A bearing for supporting the rotor and the output shaft;
A housing formed to hold the bearing in place and to surround the rotor;
A stepping motor comprising a stator in which a coil is wound around a pair of U-shaped cores sandwiched between the permanent magnets and disposed on one magnetic pole area of the permanent magnet.

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