JP2013115948A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a bearing plate to a yoke and an end plate using a simple structure.SOLUTION: In a stepping motor, a cylindrical yoke 42 is arranged so as to surround a rotational shaft 21, a plurality of pole teeth 43 are provided around the rotational shaft 21 on an inner periphery of the yoke 42, recesses 44 are formed between the pole teeth, protrusions 63 are provided on an outer periphery of a bearing plate 6, step portions 64 are provided on the yoke side of the protrusions 63 in the outer periphery of the bearing plate 6, the step portions 64 are stored in the recesses 44 formed in the inner periphery of the yoke, a storage portion 71 is formed in an end plate 7, the protrusions 63 of the bearing plate enter the storage portion 71, and fixing the end plate 7 to an end surface of the yoke 42 allows the bearing plate 6 to be fixed to the yoke 42 via the end plate 7.

Description

  The present invention relates to a stepping motor that supports a rotating shaft with a bearing plate.

  A stepping motor is a motor whose rotating shaft rotates in accordance with an input pulse signal, and is used in an optical drive, a digital camera, or the like. As a configuration of such a stepping motor, for example, a cylindrical yoke made of a soft magnetic material is covered around a rotating shaft provided with a cylindrical permanent magnet, and an excitation coil is wound around the yoke. The bobbin is stored.

  In this type of stepping motor, the end of the rotating shaft opposite to the drive portion is supported by a bearing plate disposed at the yoke end. The bearing plate is fixed to an end plate provided with a hole by welding or press fitting. By fixing this end plate to the yoke end surface by welding or the like, the bearing plate is fixed to the yoke (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-295070

  However, in such a configuration, when the bearing plate is firmly fixed to the end plate, a part of the bearing plate protrudes greatly from the end surface of the yoke, and the entire size of the bearing plate and the motor cannot be reduced. It was. Further, in the assembling process, a two-stage process is required in which the bearing plate is fixed to the end plate in advance by press fitting or the like, and the end plate is fixed to the yoke by welding or the like. Moreover, in the assembly process, the positioning of each member must be taken into account, and there is a problem in that much time is required for assembly.

  The present invention has been proposed in order to solve the above-described problems of the prior art. The object of the present invention is to fix the bearing plate to the yoke and the end plate with a simple structure. Another object of the present invention is to provide a stepping motor capable of reducing the size of the entire motor.

The stepping motor of the present invention is configured as follows.
(A) It is comprised from a rotating shaft and the cylindrical yoke arrange | positioned so that a rotating shaft may be surrounded. A plurality of pole teeth are provided around the rotation axis on the inner periphery of the yoke. A recess is formed between the pole teeth.
(B) A bearing plate is disposed at the end of the cylindrical yoke and supports one end of the rotating shaft. An end plate is disposed on the opposite side of the bearing plate from the yoke, and fixes the bearing plate to the yoke.
(C) A convex portion is provided on the outer periphery of the bearing plate, and its bottom surface is in contact with the yoke.
(D) A step portion is provided on the yoke side of the convex portion on the outer periphery of the bearing plate. Furthermore, this step is accommodated in a recess formed in the inner periphery of the yoke.
(E) The storage part is formed in the end plate, and the convex part of the bearing plate enters the storage part.
(F) The bearing plate is fixed to the yoke via the end plate by fixing the end plate to the end surface of the yoke.

  According to the present invention as described above, the bearing plate is firmly fixed to the yoke and the end plate, and the entire size of the bearing plate and the motor is further reduced while providing a simple structure in which the bearing plate is provided with the stepped portion and the convex portion. be able to. Furthermore, since the convex part and the step part of the bearing plate are integrally provided, the structure of the bearing plate can be made compact and the strength of the convex part can be increased, thereby reducing the height of the convex part. Can be reduced in size. Further, since the bearing plate is fixed so as to be sandwiched between the end plate and the yoke, it is not necessary to fix the bearing plate to the yoke or the end plate by press fitting or the like when the motor is assembled. The process can be completed once and work efficiency and production efficiency can be improved.

It is a motor axial direction sectional view showing the whole stepping motor composition of an embodiment of the present invention. It is the upper perspective view which decomposed | disassembled the principal part of the stepping motor. It is the downward perspective view which decomposed | disassembled the principal part of the stepping motor. (A) is a principal part top view of a stepping motor, (b) is the sectional view on the AA line of (a), (c) is the sectional view on the BB line of (a). (A) is a perspective view which shows the cover used for a stepping motor, (b) is a motor axial direction sectional drawing which shows the state which attached the cover to the motor.

  The stepping motor according to the present embodiment will be described in detail with reference to the drawings. First, the overall configuration of the stepping motor will be described, and then the configuration of the main part will be described in detail. Furthermore, the arrangement and assembly aspects of each part will be described.

(1. Overall configuration)
As shown in FIG. 1, the stepping motor 1 is roughly composed of a rotor 2 that rotates by a rotating magnetic field and a stator 3 that generates the rotating magnetic field.

  A part of the rotating shaft 21 of the rotor 2 is accommodated inside the stator 3, and the remaining part projects outside. A permanent magnet 22 is disposed around the portion of the rotating shaft 21 accommodated in the stator 3. The permanent magnet 22 is magnetized in multiple poles alternately with NSNS... On the circumference, and is opposed to the stator 3 with a predetermined interval. A portion of the rotating shaft 21 protruding outside the stator 3 is provided with a threaded portion on the surface thereof. Although not shown, a nut or the like is fitted into the threaded portion, the nut is moved by the rotation of the rotating shaft 21, and other members are moved through the nut.

  The stator 3 includes two stator units 3a and 3b, and these two stator units 3a and 3b are arranged so as to overlap in the motor axis L direction. Each of the two stator units 3 a and 3 b includes an outer yoke 42, a coil bobbin 5, and an inner yoke 41 that sandwiches and supports the coil bobbin 5 between the outer yoke 42.

  The inner yoke 41 and the outer yoke 42 are made of a soft magnetic material. The inner yoke 41 is an annular member, and the outer yoke 42 is a cylindrical member. In each inner peripheral portion, a plurality of pole teeth 43 are provided along the motor axis L direction, and are arranged at equal circumferential positions. The outer peripheral edge of the inner yoke 41 is fitted and fixed to the outer peripheral edge of the outer yoke 42 to form one yoke (also referred to as a stator core). The respective pole teeth 43 are arranged alternately in the circumferential direction inside the stator 3 and face the permanent magnet 22 of the rotor 2.

  A terminal pin 51 is provided on the coil bobbin 5, and an end of the exciting coil is gripped by the terminal pin 51 and wound around the peripheral surface of the coil bobbin 5.

  The bearing plate 6 is attached to the end of the outer yoke 42 of the stator unit 3b, and supports one end of the rotating shaft 21 accommodated in the stator 3. In the present specification, this one end is defined as a counter output end, and the other end extending outside the stator 3 is defined as an output end. An end plate 7 is attached and fixed to the end surface of the stator 3 so as to cover the bearing plate 6.

  The output end of the rotating shaft 21 is supported by the motor mounting plate 8. The motor mounting plate 8 is a base end side vertical portion 81 fixed to the output end side end surface of the stator 3, a horizontal portion 82 standing vertically therefrom, and is bent at a right angle from the tip of the horizontal portion 82, and is on the base end side It has a front end side vertical portion 83 extending in parallel with the vertical portion 81. The distal end side vertical portion 83 is provided with an output end side bearing plate 9. The rotating shaft 21 extends from the stator 3 through a hole 81a provided in the base end side vertical portion 81 and is rotatably supported by the output end side bearing plate 9. The horizontal portion 82 is provided with a hole 82a. Through this hole 82a, the stepping motor 1 is attached to various devices by bolting or the like.

(2. Main components)
The configuration of the outer yoke 42, the bearing plate 6, and the end plate 7, which are the main parts of the present embodiment, will be described in detail with reference to FIGS.

(2-1. Outer yoke)
The outer yoke 42 is provided in each of the stator units 3a and 3b. In this embodiment, the outer yoke 42 of the stator unit 3b on the counter-output end side will be described.

  In the present embodiment, as shown in FIG. 2, the outer yoke 42 includes a plurality of pole teeth 43. The plurality of pole teeth 43 are provided at circumferentially equidistant positions, and a plurality of recesses 44 that are recessed in the radial direction from the inner periphery to the outer periphery are formed between the pole teeth 43. The plurality of recesses 44 have the same shape and are formed at equal intervals.

(2-2. Bearing plate)
The bearing plate 6 is a disk member having a predetermined thickness and is formed of a resin molded product. In the present embodiment, the side positioned on the outer yoke 42 side is the bottom surface, and the side positioned on the end plate 7 side is the outer surface. A cylindrical bearing portion 61 that supports the rotary shaft 21 is provided on the bottom surface side of the bearing plate 6. A through hole 62 is provided on the base bottom surface of the bearing portion 61 so as to pass out to the outer surface side.

  As shown in FIG. 2, a convex portion 63 is formed on the outer surface side of the bearing plate 6. The convex part 63 protrudes from the outer peripheral part of the bearing plate 6 to the end plate 7 side, and further protrudes radially outward.

  As shown in FIG. 3, a stepped portion 64 is formed on the surface of the protruding portion 63 protruding outward from the surface on the outer yoke 42 side. The step portion 64 is formed so as to protrude outward in the radial direction of the bearing plate 6 from the peripheral surface of the bearing plate 6. At least a part of the convex part 63 projects outward from the step part 64. In addition, the step part 64 is smaller than the convex part 63, and the peripheral edge does not protrude from the peripheral edge of the convex part 63. That is, when viewed from the outer surface side of the bearing plate 6, the stepped portion 64 is preferably configured such that the outer periphery of the stepped portion 63 is covered and not exposed. The step portion 64 is formed in a size that can be accommodated in the concave portion 44 of the outer yoke 42. It should be noted that this stepped portion 64 may be set to a size that contacts the inner surface of the concave portion 44 of the outer yoke 42. Positioning of the bearing plate 6 and the outer yoke 42 is achieved by fixing the tip end portion and the side surface portion of the stepped portion 64 to the inner surface of the concave portion 44, and the fixing strength is improved.

  As shown in FIG. 3, the bearing plate 6 has two step portions 64 and two convex portions 63, and is disposed at positions that are symmetrical with respect to the motor axis L of the bearing plate 6. Further, as shown in FIG. 2, a notch 65 is formed on the outer surface side of the bearing plate 6 from a part of the surface to reach the through hole 62 from the outer peripheral edge.

(2-3. End plate)
The end plate 7 is a thin metal disk. As shown in FIG. 2, a substantially T-shaped hole 71 is provided at the center of the disc as a storage portion for the convex portion 63 of the bearing plate 6. The leaf spring 72 extends from the T-shaped base portion toward the horizontal portion, and the tip thereof is located at the circle center of the end plate 7 as shown in FIG. As shown in FIG. 4C, the leaf spring 72 is cut and raised so as to be inclined at a predetermined angle with respect to the surface of the end plate 7, and is bent so as to be a gentler angle than the initial angle. The T-shaped horizontal portion is sized to be stretched along the outer peripheral surface of the two convex portions 63 of the bearing plate 6.

(3. Arrangement of each part)
The arrangement of the outer yoke 42, the bearing plate 6 and the end plate 7 will be described with reference to the assembling method. In addition, the arrangement of these parts and other parts will be briefly described.

(3-1. Arrangement of bearing plate)
The bearing plate 6 is disposed with the bottom surface side on which the bearing portion 61 is provided facing the inside of the outer yoke 42. At this time, as shown in FIG. 4B, the two stepped portions 64 of the bearing plate 6 are aligned so as to enter the two concave portions 44 that are positioned symmetrically with respect to the motor axis L, respectively. When the stepped portion 64 is accommodated in the recess 44, the bearing plate 6 is restricted from moving in the direction of the motor axis L, and the peripheral surface is in contact with the root portion of the pole tooth 43 provided on the inner peripheral portion of the outer yoke 42. Fixed in contact. Further, the stepped portion 64 also restricts the circumferential movement of the bearing plate 6. The convex portion 63 of the bearing plate 6 is placed on the outer yoke 42 side surface, that is, the bottom surface on the end surface near the concave portion 44 of the outer yoke 42, and the height position of the bearing plate 6 and the outer yoke 42 is fixed. The As a result, only the convex portion 63 provided on the outer surface side of the bearing plate 6 is in a state of protruding from the end surface of the outer yoke 42.

(3-2. End plate arrangement)
After the arrangement of the bearing plate 6 is completed, the end plate 7 is attached to the end surface of the outer yoke 42. The end plate 7 is aligned by placing two convex portions 63 of the bearing plate 6 protruding from the end surface of the outer yoke 42 along the outer peripheral surface in the T-shaped horizontal portion of the hole 71. Further, the leaf spring 72 is made to enter the notch 65 of the bearing plate 6. Furthermore, the tip of the leaf spring 72 that is obliquely cut and raised from the surface of the end plate 7 is located immediately above the through hole 62 of the bearing plate 6.

  At this time, as shown in FIGS. 4A and 4C, the outer surface of the bearing plate 6 is in contact with the yoke-side surface of the end plate 7, that is, the lower surface. Then, as shown in FIG. 4B, the yoke-side surface, that is, the bottom surface of the convex portion 63 is placed on the end surface of the outer yoke 42.

  The end plate 7 is fixed to the end surface of the outer yoke 42 by welding or an adhesive. Thus, the bearing plate 6 is sandwiched between the outer yoke 42 and the end plate 7 and is fixed to the outer yoke 42 via the end plate 7.

(3-3. Arrangement of other parts)
After fixing the end plate 7, the coil bobbin 5 is attached between the outer peripheral surface of the outer yoke 42 and the pole teeth 43. Further, the outer yoke 42 and the inner yoke 41 are combined to constitute the stator unit 3b. Further, the output end side bearing plate 9 is installed in the distal end side vertical portion 83, and the outer yoke 42 constituting the stator unit 3 a is attached to the proximal end side vertical portion 81 of the motor mounting plate 8. The rotary shaft 21 is inserted into the outer yoke 42, the tip end side of the rotary shaft 21 is fitted to the bearing plate 9, and the coil bobbin 5 is attached between the outer peripheral surface of the outer yoke 42 and the pole teeth 43. The stator 41 is combined with the yoke 41. Further, the stator unit 3b is inserted through the rotating shaft 21, and the stator unit 3a and the stator unit 3b are joined to constitute the stator 3, whereby the stepping motor 1 is completed. At this time, the non-output end of the rotating shaft 21 is accommodated in the bearing portion 61 of the bearing plate 6, is inserted through the through hole 62, contacts the leaf spring 72 of the end plate 7, and is locked. The pole teeth 43 of the outer yoke 42 and the inner yoke 41 are arranged around the rotating shaft 21 and surround the permanent magnet 22. The bearing plate 6 on the non-output end side and the bearing plate 9 on the output end side support a radial load of the rotating shaft 21 as a radial bearing. Further, the leaf spring 72 urges the rotating shaft 21 toward the output end side by its elastic force, and supports the axial load of the rotating shaft 21 as an axial bearing.

(4. Effects of the present embodiment)
(1) In the present embodiment, the stepped portion 64 provided on the outer periphery of the bearing plate 6 of the stepping motor 1 is accommodated in the concave portion 44 formed between the pole teeth 43 of the outer yoke 42 and the convex portion 63 of the bearing plate. The bearing plate 6 is placed on the outer yoke 42 with the bottom surface of the outer yoke 42 placed on the end surface near the recess 44 of the outer yoke 42. Further, the convex portion 63 provided on the outer surface side of the bearing plate 6 is inserted into the hole portion 71 provided in the end plate 7. That is, the bearing plate 6 is attached to the outer yoke 42 and then fixed to the outer yoke 42 via the end plate 7. Thus, it is not necessary to make the bearing plate 6 protrude greatly from the end plate 7 and be fixed. Furthermore, while the bearing plate 6 has a simple structure, the bearing plate 6 can be firmly fixed to the outer yoke 42 and the end plate 7, and the size of the bearing plate 6 and the entire motor can be reduced.

(2) Furthermore, a stepped portion 64 that is smaller than the convex portion 63 and does not protrude from the periphery is provided on the yoke-side surface of the convex portion 63 of the bearing plate 6. Accordingly, the stepped portion 64 and the convex portion 63 protrude at the same position in the radial direction of the bearing plate 6 and are integrally configured. Therefore, the bearing plate 6 can have a compact structure, and the strength of the convex portion 63 can be increased. Furthermore, the height of the convex part 63 itself can be reduced, and the whole motor can be reduced in size.

(3) Since the bearing plate 6 is fixed so as to be sandwiched between the end plate 7 and the outer yoke 42, the bearing plate 6 is fixed to the outer yoke 42 or the end plate 7 by welding or the like when the motor is assembled. There is no need to do this, and only one step of fixing the end plate 7 by welding or the like is sufficient. That is, work efficiency and production efficiency can be improved.

(4) In the present embodiment, two convex portions 63 and two step portions 64 of the bearing plate 6 are provided, and each is disposed at a position that is symmetrical with respect to the motor axis L of the bearing plate 6. Thus, when the end plate 7 is fixed to the end face of the outer yoke 42, the end plate 7 may be aligned so that the outer peripheral edge of the hole 71 is aligned with the outer periphery of the two convex portions of the bearing plate 6 fixed previously. Easy to assemble.

(5) In the present embodiment, a leaf spring 72 extending from the outer peripheral portion of the end plate 7 to the central portion of the hole portion 71 is provided, a part of the outer surface of the bearing plate 6 is cut away, and the leaf spring 72 is inserted. A notch portion 65 is provided. As a result, the tip of the leaf spring 72 is positioned immediately above the through hole 62 of the bearing plate 6, and the rotary shaft 21 inserted through the through hole 62 can be locked by the leaf spring 72.

(5. Other embodiments)
The present invention is not limited to the illustrated embodiment, and includes other embodiments as described below.
(1) For example, a metal cover 73 as shown in FIG. 5A may be attached to the end plate 7 to protect the leaf spring. As shown in FIG. 5B, the cover 73 is overlapped on the end surface of the end plate 7 and fixed by welding or the like.

(2) In the above-described embodiment, the inner yoke 41 is an annular member and the outer yoke 42 is a cylindrical member. However, the yoke 41 may be a cylindrical member and the outer yoke 42 may be an annular member.

(3) Although the bearing plate 6 which is a sliding bearing formed of a resin molded product is used as a bearing that rotatably supports the rotating shaft 21, a sliding bearing, a ball bearing, a roller bearing, or the like formed of a sintered material is used. May be used.

(4) In the present embodiment, two convex portions 63 and two step portions 64 of the bearing plate are provided, but three or more of each may be provided. In that case, the stepped portion 64 is provided at a position where it engages with the concave portion of the outer yoke 42. The hole 71 of the end plate 7 may have a shape that spans the entire protrusion 63, or may have a plurality of holes so as to engage with each other.

(5) In the present embodiment, the hole 71 is provided as a storage portion for the end plate 7, and the convex portion 63 of the bearing plate 6 is inserted into the hole 71, so the convex portion 63 of the bearing plate is the end plate 7. Is exposed from. Not only this but a recessed part may be provided as an accommodating part of the end plate 7, and the convex part 63 of the bearing plate 6 may be accommodated in this recessed part.

(6) The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Rotor 21 Rotating shaft 22 Permanent magnet 3 Stator 3a 3b Stator unit 41 Inner yoke 42 Outer yoke 43 Polar tooth 44 Recess 5 Coil bobbin 51 Terminal pin 6 Bearing plate 61 Bearing part 62 Through hole 63 Projection part 64 Step part 65 Cutting Notch 7 End plate 71 Hole 72 Leaf spring 73 Cover 8 Motor mounting plate 81 Base end side vertical portion 81a Hole portion 82 Horizontal portion 82a Hole portion 83 Front end side vertical portion 9 Output end side bearing plate L Motor axis

Claims (4)

A rotation axis;
A cylindrical yoke that is disposed so as to surround the rotating shaft and includes a plurality of pole teeth provided around the rotating shaft on an inner peripheral portion and a recess formed between the pole teeth;
A bearing plate disposed at an end of the cylindrical yoke and supporting one end of the rotating shaft;
A stepping motor disposed on the opposite side of the bearing plate from the yoke and having an end plate for fixing the bearing plate to the yoke;
The outer periphery of the bearing plate is provided with a convex portion whose bottom surface comes into contact with the yoke,
A step portion is provided on the yoke side of the convex portion on the outer periphery of the bearing plate, and the step portion is accommodated in the concave portion formed on the inner peripheral portion of the yoke,
A storage portion is formed in the end plate, and the convex portion of the bearing plate enters the storage portion,
A stepping motor characterized in that the bearing plate is fixed to the yoke through the end plate by disposing the end plate on the end surface of the yoke.   The stepping motor according to claim 1, wherein the bearing plate includes a plurality of the stepped portions and the convex portions.   3. The stepping motor according to claim 1, wherein a tip portion or both side surface portions of the stepped portion are in contact with an inner surface of the concave portion formed in an inner peripheral portion of the yoke. The bearing plate is provided with a bearing portion that supports a rotating shaft on the yoke side,
A through-hole penetrating to the end plate side of the bearing plate is formed on the bottom surface of the bearing portion,
The end plate is provided with a leaf spring cut and raised from the outer peripheral portion toward the through hole,
A part of the surface on the end plate side of the bearing plate is notched, and a notch portion into which a leaf spring is inserted is formed.
4. The stepping motor according to claim 1, wherein the rotating shaft is inserted through the through hole and abuts against a leaf spring and is urged by the leaf spring. 5.

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