JP4794555B2 - Stepping motor - Google Patents

Description

  The present invention relates to a PM type (permanent magnet type) stepping motor. In particular, the present invention relates to a thin PM type stepping motor that can be manufactured at low cost.

The structure of a conventional PM type stepping motor (example of two phases, 20 steps / 1 rotation) will be described.
FIG. 11 is an overall view of a conventional PM type stepping motor.
12 is a side sectional view of the stepping motor of FIG.
FIG. 13 is an exploded perspective view of the stepping motor of FIG.
As shown in FIG. 12, the PM type stepping motor 501 is mainly configured by a rotor 510 having a rotation shaft and a cylindrical stator 520 disposed so as to surround the rotor 510.

  The rotor 510 is a substantially cylindrical permanent magnet 511, and a rotating shaft 513 is fixed through the shaft core of the magnet 511. One end (the right end in the figure) of the rotating shaft 513 is supported by the yoke 543 via a bearing 515, and the other end (the left end in the figure) also has a frame (not shown) via a bearing (not shown). It is supported by. On the outer peripheral surface of the permanent magnet 511, a plurality (10 in this example) of N poles and S poles extending in the rotation axis direction are alternately magnetized in the circumferential direction.

  Stator 520 has an A-phase stator 521A and a B-phase stator 521B arranged in the direction of rotating shaft 513. The A-phase stator 521A and the B-phase stator 521B are configured by combining two claw pole type magnetic pole pieces 523a and 523b, 523c and 523d. The claw pole type magnetic pole piece 523 has a ring-shaped flange portion and a plurality (five in this example) of triangular pole teeth 525 (see FIG. 13) extending in the rotation axis direction from the inner peripheral edge of the flange portion. Such a claw pole type magnetic pole piece 525 is usually manufactured by punching or bending a disk-shaped plate with a press or drawing. Each stator 521 has two claw pole type magnetic pole pieces 523 arranged so that the pole teeth 525 face each other alternately and in a non-contact manner. Thus, a concave portion having a U-shaped cross section is formed between the flange portion and the pole teeth of each magnetic pole piece. The A-phase stator 521A and the B-phase stator 521B are arranged such that the pole teeth 525 are displaced in the 1/2 pitch circumferential direction. Both stators arranged in this manner are integrally fixed by a bobbin 527. The bobbin 527 is formed so that resin covers the outer peripheral surface of each stator 521 and is filled between the pole teeth 525.

  A coil 531A and 531B are formed by winding a winding in a recess formed between the flange portion and the pole teeth of each pole piece covered with the bobbin 527. Each coil 531 is insulated from each stator 521 by a bobbin 527. Between the recesses of the bobbin 527, a terminal block 528 protruding outward is formed. The terminal block 528 is provided with terminal pins 551 for supplying power to each coil (see FIGS. 11 and 12).

  As shown in FIG. 12, the magnetized portion of the outer peripheral surface of the permanent magnet 511 of the rotor 510 and the inner peripheral surface of the pole teeth 525 of each magnetic pole piece 523 of the stator 520 are opposed to each other with a predetermined gap. Be placed. When the coil 531 is energized and the stator 521 is excited, N poles and S poles are alternately generated in the pole teeth 525 alternately arranged in the circumferential direction of the stator 521. Between these magnetic poles and the magnetic poles magnetized on the permanent magnet 511 (specifically, the inner peripheral surface of the pole teeth 525 of the claw pole type magnetic pole piece 523 and the permanent magnet 511 extending in the rotation axis direction) A magnetic field is generated between the surface of the magnetic part). By alternately energizing the coils 531A and 531B of the A-phase stator 521A and the B-phase stator 521B, repulsion and attraction occur between the magnetic poles, and the rotor 510 continuously rotates in one direction.

  In order to generate a torque sufficient to rotate the rotor 510 and the object connected to the rotor 510, the magnetic field acting between the magnetic poles of the rotor 510 and the stator 520 needs to have sufficient strength. For this purpose, the inner peripheral surface of the pole teeth 525 of the claw pole type magnetic pole piece 523 and the magnetized portion of the outer peripheral surface of the permanent magnet 511 need to have a sufficient magnetic flux density. Therefore, by making the pole teeth 525 triangular as described above, the magnetic pole density on the stator 510 side is increased as much as possible to increase the magnetic flux density.

  With the configuration as described above, there is a problem that the stepping motor cannot be made thinner than a certain degree. Further, as shown in FIG. 11 and FIG. 12, since the terminal block for feeding the coil protrudes from the side surface of the motor, the degree of freedom of the motor arrangement posture is low.

  The present invention has been made in view of the above problems, and an object thereof is to provide a thin stepping motor.

  The stepping motor of the present invention includes a rotor composed of a permanent magnet having a plurality of N poles and S poles alternately magnetized on the outer periphery, a rotating shaft of the rotor, and a plurality of coils arranged so as to surround the rotor. A stepping motor comprising: a ring-shaped magnetic pole piece having a magnetic pole on its inner periphery; and a stator including a coil that magnetizes the magnetic pole piece, wherein the magnetic pole piece includes a flange portion and the flange portion. It has pole teeth protruding in the axial direction from the inner peripheral edge, and the coil is arranged in the outer peripheral area of the flange portion of the magnetic pole piece.

  According to the present invention, since the entire magnetic pole piece including the flange portion can be accommodated in the inner peripheral area of the coil, the thickness of the motor can be reduced (shortened).

  Another stepping motor of the present invention is arranged so as to surround a rotor composed of a permanent magnet having a plurality of N poles and S poles alternately magnetized on the outer periphery, a rotating shaft of the rotor, and the rotor. A stepping motor comprising: a ring-shaped magnetic pole piece having a plurality of magnetic poles on its inner periphery; and a stator including a coil for magnetizing the magnetic pole piece, wherein the magnetic pole piece is made of a magnetic plate. The magnetic pole is a protrusion formed only on the inner periphery of the magnetic pole piece and projects only inward, and the coil is disposed in the outer peripheral area of the magnetic pole piece.

The molding process of the stepping motor of the present invention is only an iron plate punching process, and the entire molding cost including the mold cost can be reduced. In addition, since it can be molded easily, it is easy to increase the resolution by increasing the number of protrusions. Note that if the number of pole pieces is increased (for example, one phase is a set of two (a total of four)). Torque can be increased.

  In the present invention, it is preferable that the magnetic pole piece is obtained by punching an electromagnetic soft iron plate or a silicon steel plate.

  In the present invention, two coils are arranged in the axial direction, and the magnetic pole pieces are arranged on the inner circumference of each coil by shifting the positions of the two magnetic poles. A circular center yoke that is in contact with the magnetic pole piece and is disposed between the inner side faces in the axial direction, and covers the outer and outer peripheral faces in the axial direction of each coil. It is preferable to comprise a piece and an outer yoke in contact with the center yoke.

  According to the present invention, by providing the outer yoke and the center yoke, the strength of the magnetic field formed around the coil is increased, and the pole piece is easily magnetized.

  In the present invention, the coil further includes a collective wiring member for feeding the coil attached to an outer surface of the outer yoke or its connecting member (also referred to as a casing), Are preferably connected.

  In this way, there is no need to provide a terminal block for supplying power to each coil. In the case of the claw pole type, as shown in FIG. 5, it is common to provide a terminal block on the bobbin and to erect terminal pins on the same table. In the present invention, the flexible substrate can be connected to the end surface of the motor with flexibility in the terminal processing, and the starting end and the terminal end of the coil can be easily connected to the substrate. Further, since a terminal block is unnecessary, the degree of freedom in design (wiring) is high, which is advantageous for the outer diameter restriction.

  As is apparent from the above description, according to the present invention, a thin stepping motor can be provided. Further, it is possible to provide a stepping motor that can be manufactured at a lower cost than the claw pole type.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side cross-sectional view for explaining the structure of a stepping motor (example of two phases, 8 steps / 1 rotation) according to the first embodiment of the present invention.
FIG. 2 is an exploded perspective view of the stepping motor of FIG.
FIG. 3 is an exploded perspective view showing a state in which a part of the stepping motor of FIG. 1 is assembled.
The stepping motor 1 is mainly composed of a rotor 10 having a rotating shaft and a cylindrical stator 20 arranged so as to surround the rotor 10.

  As shown in FIG. 1, the rotor 10 has a cylindrical permanent magnet 11, and a rotating shaft 13 (for example, made of stainless steel) is passed through and fixed to the shaft core of the magnet 11. Both ends of the rotating shaft 13 are rotatably supported by the resin bearing 15. On the outer peripheral surface of the permanent magnet 11, a plurality of N poles and S poles extending in the rotation axis direction are alternately magnetized in the circumferential direction (four in this example). The centers of both end faces of the permanent magnet 11 are curled up in a conical shape to reduce the weight. Resin washers 17 are fixed to both end faces.

  The stator 20 has an A-phase stator 21A and a B-phase stator 21B arranged in the direction of the rotation shaft 13 of the rotor 10. The A-phase stator 21A and the B-phase stator 12B are configured by combining two magnetic pole pieces 23a and 23b and 23c and 23d having the same shape. As shown in FIG. 2B, the pole piece 23 is a plate material of a substantially ring-shaped magnetic body (for example, made of electromagnetic soft iron or silicon steel plate), and has a ring-shaped flange portion 24 and an inner peripheral edge of the flange portion 24. A plurality of (in this example, two) pole teeth 25 projecting in the axial direction from the base. Each pole tooth 25 is located diagonally with respect to the center of the pole piece 23. Depending on the number of steps, the position of the pole teeth 25 is not diagonal. The pole teeth 25 are tapered and substantially trapezoidal, and the length in the axial direction is shorter than the pole teeth 425 of the conventional claw pole type magnetic pole piece 423 shown in FIG. The inner peripheral surface of each pole tooth 25 is curved in an arc shape, and the length in the circumferential direction is slightly shorter than the length of the fan-shaped arc having a central angle of 90 ° in this example.

  In each stator 21 of this example, two ring-shaped magnetic pole pieces 23 are partially overlapped in the axial direction so that the pole teeth 25 face each other alternately in the circumferential direction, And it fixes so that some clearance gaps (Yg of FIG. 1 (A)) may open between the flange parts 24. FIG. In addition, by making the shape of the pole teeth 25 into a tapered trapezoidal shape, the pole teeth 25 of the two magnetic pole pieces 23 can be arranged so as to partially overlap in the axial direction.

  The A-phase stator 21A and the B-phase stator 21B are arranged such that the pole teeth 25 of the pole piece 23 are displaced in the 1/2 pitch circumferential direction. That is, as shown in FIG. 3, the magnetic pole pieces 23 a, 23 b, 23 c, and 23 d are arranged so as to be shifted in the circumferential direction in the 1/2 pitch circumferential direction of the pole teeth 25. At this time, an alignment portion is formed on each pole piece so as to facilitate the alignment of the two pole pieces and the alignment of each phase stator. Further, the A-phase stator 21A and the B-phase stator 21B are arranged with a ring-shaped center yoke (for example, made of electromagnetic soft iron) 41 in the direction of the rotation axis, and a gap is opened between the two stators. Both the stators 21 and the center yoke 41 arranged in this way are integrally fixed by a bobbin 27. The bobbin 27 is formed by filling resin between the magnetic pole pieces 23 of each stator 21 and the outer periphery.

  With the configuration described above, as shown in FIG. 1A, each magnetized portion of the outer peripheral surface of the permanent magnet 11 of the rotor 10 has an inner portion of each protrusion 25 of the magnetic pole piece 23 of the stator 20. The end faces are opposite.

  Here, the distance Yg between the magnetic pole pieces 23 of each stator 21 is the distance between the rotor 10 and the stator 20 of the motor (between the magnetized portion of the permanent magnet 11 and the inner end face of the magnetic pole piece 23). Distance) is equal to or greater than Ag. By setting the distance between the gaps in this way, there is an advantage that a magnetic short circuit can be avoided and the strength of the magnetic field is increased, contributing to an improvement in torque.

  Windings 29A and 29B (self-bonding copper wires in this example) are wound around the outer peripheral surface of the bobbin 27 on the outer peripheral surface of the magnetic pole piece 23 of each stator 21 to form coils 31A and 31B. . That is, the coil 31 is disposed in the outer peripheral area of the magnetic pole piece 23 (including the flange portion). In FIG. 1, the coil 31 is depicted as being wound directly on the outer peripheral surface of the pole piece 23, but it is preferable to provide a resin layer also on the outer periphery of the pole piece 23. In this example, the coil 31 is insulated from the stator 21 by varnish or the like.

  The A-phase stator 21A, the center yoke 41, and the B-phase stator 21B (referred to as stator assembly) that are fixed by the bobbin 27 along the rotation axis direction are fitted on the concentric cylinder in the outer yoke 43 (for example, made of electromagnetic soft iron). The yoke 43 is fixed. Here, in the stator assembly, as shown in FIG. 1, the two magnetic pole pieces 23 a and 23 d located on both outer sides in the axial direction and the center yoke 41 are fixed in contact with the outer yoke 43. The outer yoke 43 is composed of a cup-shaped outer yoke piece that is divided in the axial direction of the motor. A window 45 is formed on the outer peripheral surface of the outer yoke 43. From this window 45, the start end and the end of the winding 29 of each coil 31 are drawn out. In addition, an opening to which the bearing 15 is fixed is formed on the end surface of the outer yoke 43.

With the configuration as described above, the strength of the magnetic field around each coil 31 is increased, and the pole piece 23 is easily magnetized.
Specifically, as shown in FIG. 1B, the stator 21B has an axially outer end surface (right surface in the drawing) and outer peripheral surface (lower surface in the drawing) of the coil 31A. The end surface and the side surface of the yoke 43 are covered, and the end surface on the inner side in the axial direction (the left surface in the drawing) is in contact with the end surface of the center yoke 41. Further, the two magnetic pole pieces 23 c and 23 d are located between the end face of the outer yoke 43 and the end face of the center yoke 41. The outer yoke 43 and the center yoke 41 increase the strength of the magnetic field M formed around the coil 31A. Thereby, each magnetic pole piece 23 between the outer yoke 43 and the center yoke 41 is easily magnetized.

  In this stepping motor, since the magnetic pole piece 23 is disposed in the inner peripheral area of the coil 31, the thickness of the stator 21 can be reduced, and thus the thickness of the motor 1 can be reduced.

FIG. 4 is a diagram illustrating an example of a state in which the stepping motor of FIG. 1 is attached.
In this example, one end surface of the motor 1 is fixed to the base plate 60, and a flexible substrate (collective wiring member) 70 for energizing the motor is attached to the other end surface.
One outer yoke end surface of the motor 1 is fixed to the base plate 60 by bonding or the like. The flexible substrate 70 has, for example, a terminal portion 71 having an end surface shape of the motor 1, and is fixed to the other outer yoke end surface of the motor 1 at the same portion. Then, the start and end of the coil windings 29A and 29B of each phase are drawn out to the surface of the terminal portion 71 of the flexible substrate 70, and are electrically connected to each power supply line by soldering or the like. In this way, the motor can be kept thin even after the end treatment of the coil.

FIG. 5 is a side cross-sectional view illustrating the structure of a stepping motor (example of two phases, 20 steps / 1 rotation) according to a second embodiment of the present invention.
FIG. 6 is an exploded perspective view of the stepping motor of FIG.
FIG. 7 is an exploded perspective view showing a state in which a part of the stepping motor of FIG. 5 is assembled.
The stepping motor 101 of this example has substantially the same configuration as the stepping motor 1 of FIG. 1 (however, an example of two phases, 20 steps / revolution), but the structure of the pole pieces of each stator is different. In the figure, parts / members having the same configuration and operation as those of the stepping motor of FIG. 1 are denoted by the same reference numerals as those in FIG.

  The A-phase stator 121A and the B-phase stator 121B in this example are configured by combining two magnetic pole pieces 123a and 123b, 123c and 123d having the same shape. As shown in FIG. 6B, the magnetic pole piece 123 is a plate material of a substantially ring-shaped magnetic body (electromagnetic soft iron) having a predetermined plate thickness (0.3 mm in this example), and is radially extending from the inner peripheral end. A plurality (five in this example) of protrusions 125 are formed. Each protrusion 125 is located at an equally spaced angle with respect to the center of the pole piece 123 (in this example, a central angle of 72 °). Further, the inner end face of each projection 125 is arcuate, and the circumferential length is the length of a fan-shaped arc having a central angle of 36 ° in this example. Such a ring-shaped magnetic pole piece 123 is produced by punching an electromagnetic soft iron plate or a silicon steel plate.

  In each stator 21, two ring-shaped magnetic pole pieces 23 are fixed side by side with a small gap (Yg) in the rotation axis direction so that the protrusions 25 are alternately arranged in the circumferential direction and the protrusions 25 are not in contact with each other. Is done. The A-phase stator 121A and the B-phase stator 121B are arranged such that the protrusion 125 of the pole piece 123 is displaced in the 1/2 pitch circumferential direction. That is, as clearly shown in FIG. 7, the pole pieces 123 a, 123 c, 123 b, and 123 d are arranged so as to be displaced in the circumferential direction and in the 1/2 pitch circumferential direction of the protrusion 125.

  In this stepping motor, since the magnetic pole of the stator 10 is the inner end face of the protrusion 125 of the ring-shaped magnetic pole piece 123, the thickness of the stator 121 can be made as thin as the plate thickness of the magnetic pole piece 123. Further, since the ring-shaped magnetic pole piece 123 can be easily formed, for example, by punching an electromagnetic soft iron plate, it is easy to increase the number of protrusions 125 and increase the resolution.

FIG. 8 is a side sectional view for explaining the structure of a stepping motor (example of two phases, 20 steps / 1 rotation) according to a third embodiment of the present invention.
FIG. 9 is an exploded perspective view of the stepping motor of FIG.
FIG. 10 is an exploded perspective view showing a state in which a part of the stepping motor of FIG. 8 is assembled.
The stepping motor 201 of this example has substantially the same configuration as the stepping motor 101 of FIG. 5, but the structure of the pole pieces of each stator is different. In the figure, parts / members having the same configuration and operation as those of the stepping motor of FIG. 5 are denoted by the same reference numerals as those in FIG.

  In this example, two pole pieces 123 of each stator in FIG. 5 are stacked. That is, as clearly shown in FIG. 9, one pole piece 223a of the A-phase stator 221A is composed of two stacked pole pieces 123a, and the other pole piece 223b is two stacked pole pieces. 123b. Similarly, one magnetic pole piece 223c of the B-phase stator 221B is composed of two superposed magnetic pole pieces 123c, and the other magnetic pole piece 223d is composed of two superposed magnetic pole pieces 123d.

  By configuring in this way, the area of the magnetic poles of the stator can be made wider than that of the stator of FIG. 5, so that the rotational torque can be increased.

It is side surface sectional drawing explaining the structure of the stepping motor (example of 2 phases, 8 steps / 1 rotation) concerning the 1st Embodiment of this invention. It is a disassembled perspective view of the stepping motor of FIG. It is a disassembled perspective view which shows the state which assembled a part of stepping motor of FIG. It is a figure explaining an example of the state which attached the stepping motor of FIG. It is side surface sectional drawing explaining the structure of the stepping motor (Example of 2 phases, 20 steps / 1 rotation) concerning the 2nd Embodiment of this invention. FIG. 6 is an exploded perspective view of the stepping motor of FIG. 5. FIG. 6 is an exploded perspective view showing a state in which a part of the stepping motor of FIG. 5 is assembled. It is side surface sectional drawing explaining the structure of the stepping motor (Example of 2 phases, 20 steps / 1 rotation) concerning the 3rd Embodiment of this invention. It is a disassembled perspective view of the stepping motor of FIG. It is a disassembled perspective view which shows the state which assembled some stepping motors of FIG. It is a general view of a conventional PM type stepping motor. It is side surface sectional drawing of the stepping motor of FIG. It is a disassembled perspective view of the stepping motor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stepping motor 10 Rotor 11 Permanent magnet 13 Rotating shaft 15 Resin bearing 17 Washer 20 Stator 21 Stator 23 Magnetic pole piece 24 Flange part 25 Polar tooth 27 Bobbin 29 Winding 31 Coil 41 Center yoke 43 Outer yoke 45 Window 60 Base plate 70 Flexible Substrate (collective wiring member) 71 Terminal section

Claims (5)

A rotor composed of a permanent magnet having a plurality of N poles and S poles alternately magnetized on the outer periphery;
A rotation axis of the rotor;
A ring-shaped magnetic pole piece having a plurality of magnetic poles arranged so as to surround the rotor, and a stator including a coil for magnetizing the magnetic pole piece;
A stepping motor comprising:
The pole piece has a flange portion and pole teeth protruding in the axial direction from the inner peripheral edge of the flange portion,
A stepping motor, wherein the coil is disposed in an outer peripheral area of a flange portion of the pole piece. A rotor composed of a permanent magnet having a plurality of N poles and S poles alternately magnetized on the outer periphery;
A rotation axis of the rotor;
A ring-shaped magnetic pole piece having a plurality of magnetic poles arranged so as to surround the rotor, and a stator including a coil for magnetizing the magnetic pole piece;
A stepping motor comprising:
The magnetic pole piece is made of a magnetic plate, and the magnetic pole is a protrusion protruding only inwardly formed on the inner periphery of the magnetic pole piece,
A stepping motor in which the coil is disposed in an outer peripheral area of the magnetic pole piece.   3. The stepping motor according to claim 1, wherein the magnetic pole piece is obtained by punching an electromagnetic soft iron plate or a silicon steel plate. The two coils are arranged in the axial direction, and the magnetic pole pieces are arranged on the inner circumference of each coil by shifting the positions of the two magnetic poles,
further,
A circular center yoke disposed between the coils (between the inner side surfaces in the axial direction) and in contact with the magnetic pole piece;
An outer yoke that covers an outer surface and an outer peripheral surface in the axial direction of each coil, and is in contact with the axially outer magnetic pole piece and the center yoke of the magnetic pole pieces;
The stepping motor according to claim 1, 2, or 3. The coil further includes a collective wiring member for feeding the coil, which is attached to the outer surface of the outer yoke or its connecting member (also referred to as a casing).
The stepping motor according to any one of claims 1 to 4, wherein a starting end and a terminal end of the winding are connected to a power supply line of the collective wiring member.

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