JP2013146170A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a bearing plate to a yoke and an end plate with a simple structure.SOLUTION: A support part 44 is provided in an area ranging from an end part of an outer yoke 42 to a pole tooth 43, and a bearing plate 6 is housed in the outer yoke 42 so that an outer periphery and a bottom surface of the bearing plate 6 contact with the support part 44. An end plate 7 is fixed to an end part of the outer yoke 42 thereby allowing a protruding part 63 of the bearing plate 6 to be housed in the housing part 71 of the end plate 7. Further, contact between an outer end surface 62 and the end plate 7 restricts movements of the bearing plate 6 in a horizontal direction and a motor axis line L direction, and the position of the bearing plate 6 is maintained.

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 and the end plate to the yoke 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) A rotating shaft having a magnet fixed around the shaft, a cylindrical yoke surrounding the magnet, a bearing plate disposed at an end of the cylindrical yoke and supporting one end of the rotating shaft, and a yoke of the bearing plate And an end plate that is disposed on the outer end surface on the opposite side to fix the bearing plate to the yoke.
(B) A plurality of pole teeth are provided at the end of the yoke, and a support portion for supporting the bearing plate is formed on a surface facing the magnet.
(C) The bearing plate is disposed in the yoke such that the outer peripheral edge is brought into contact with a support provided at the end of the yoke.

  In this case, the support portion of the yoke end may be formed in a step shape. Further, a convex portion is provided on the outer end surface of the bearing plate, and a storage portion for storing the convex portion of the bearing plate is provided on a surface facing the bearing plate of the end plate, and the convex portion of the bearing plate is provided in the storage portion of the end plate. The end plate may be fixed to the yoke so as to enter.

  According to the present invention as described above, the bearing plate can be firmly fixed to the yoke and the end plate, and the entire bearing plate and the motor can be reduced in size while having a simple structure in which the yoke is provided with the support portion. . The bearing plate can be housed inside the yoke and assembled by simply attaching the end plate from above. As a result, there is no need to fix the bearing plate to the yoke or the end plate by press-fitting or the like at the time of motor assembly, and the bearing plate, the end plate and the yoke can be easily assembled to improve work efficiency and production efficiency. it can.

It is a motor axial direction sectional view showing the whole stepping motor composition of an embodiment of the present invention. It is an upper perspective view of the outer yoke which concerns on embodiment. It is the upper perspective view of the bearing plate which concerns on embodiment, (a) is the figure seen from the yoke side, (b) is the figure seen from the end plate side. It is an upper perspective view of the end plate which concerns on embodiment. It is an upper perspective view which shows arrangement | positioning of the outer yoke which concerns on embodiment, a bearing plate, and an end plate. (A) is the top view which looked at the stepping motor which concerns on embodiment from the end-plate side, (b) is the BB sectional drawing of (a), (c) makes a notch part inclined. It is sectional drawing which shows the contact part of the outer yoke and bearing plate at the time of doing. (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 detailed portions will be described. 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. The portion of the rotating shaft 21 that protrudes 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, and the nut is moved by the rotation of the rotating shaft 21. The other member is moved through the gap.

  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 includes an outer yoke 42, a coil bobbin 5, and an inner yoke 41 that supports the coil bobbin 5 sandwiched 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 this terminal pin 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. Detailed configuration)
Detailed configurations of the outer yoke 42, the bearing plate 6, and the end plate 7 according to the present embodiment will be described 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.

  As shown in FIG. 2, the outer yoke 42 includes a plurality of pole teeth 43. The pole teeth 43 are provided at equal circumferential positions from the end of the outer yoke 42 so as to surround the motor axis L. A support portion 44 that is recessed from the inner peripheral portion to the outer peripheral portion is formed at each end portion of the outer yoke 42 on which the pole teeth 43 are provided. In the present embodiment, the support portion 44 is formed in a step shape that is recessed outward in the radial direction, and has a side surface whose distance from the motor axis L is R and a bottom surface parallel to the outer yoke 42. In addition, a recess 45 in which an end portion of the outer yoke 42 is notched is formed between the adjacent pole teeth 43.

(2-2. Bearing plate)
The bearing plate 6 is a disk member having a predetermined radius and a radius R, and is formed of a resin molded product. In the present embodiment, the side positioned on the outer yoke 42 side (upper side in FIG. 3A) is the bottom surface, and the side positioned on the end plate 7 side (lower side in FIG. 3A) is the outer surface. As shown in FIG. 3A, a bearing hole 61 penetrating in the direction of the motor axis L is provided in the center portion on the bottom surface side of the bearing plate 6, and the rotating shaft 21 is inserted into the bearing hole 61.

  As shown in FIG. 3 (b), the outer end surface 62 on the outer surface side of the bearing plate 6 is formed with a circular recess 65 having a diameter larger than that of the bearing hole 61 at the center of the surface. A notch 64 is formed at the edge of the recess 65, and the notch 64 communicates the recess 65 with the outer peripheral surface of the bearing plate 6. The recess 65 and the notch 64 accommodate a distal end portion and a proximal end portion of a leaf spring 72 described later when the stepping motor is assembled. In addition, a protrusion 66 protruding outward in the radial direction is provided on the outer peripheral surface of the bearing plate 6. The protrusion 66 is provided with a size that is the same as or slightly smaller than the recess 45 provided in the outer yoke 42.

  The outer end surface 62 is provided with a convex portion 63 projecting vertically from the surface. In the present embodiment, three columnar convex portions 63 are provided around the concave portion 65. One is provided at a position facing the notch 64, and the other two are provided at positions equidistant from the first projection 63 at positions facing the recess 65. That is, the line connecting the three convex portions 63 forms an isosceles triangle.

(2-3. End plate)
The end plate 7 is a thin metal disk. As shown in FIG. 4, the end plate 7 is provided with a housing portion 71 and a leaf spring 72.

  The leaf spring 72 is cut and raised obliquely by 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 tip portion of the leaf spring 72 is disposed so as to abut the end portion of the rotating shaft 21 on the side opposite to the output end when the stepping motor is assembled. That is, as shown in FIG. 4, the motor axis L passes through the tip of the leaf spring 72.

  The accommodating portion 71 is provided around the leaf spring 72. In the present embodiment, there are provided three accommodating portions 71 cut into a circle. One is formed at a position facing the tip of the leaf spring 72 cut and raised. The remaining two are formed at equal distances from the first accommodating portion 71 at positions facing each other with the leaf spring 72 sandwiched from the longitudinal direction. That is, the line connecting the three accommodating portions 71 forms an isosceles triangle. The diameter of the hole of the accommodating portion 71 is formed to be equal to or slightly larger than the size of the upper surface and the lower surface of the convex portion 63 provided on the bearing plate 6.

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

(3-1. Mounting the bearing plate to the outer yoke)
As shown in FIG. 5, the bearing plate 6 is disposed with the bottom side facing the end of the outer yoke 42. Although not shown, the mounting to the outer yoke 42 is performed by inserting the bearing plate 6 into the outer yoke 42 from the bottom surface side. The bearing plate 6 is disposed in the outer yoke 42 while aligning so that the protrusion 66 enters the recess 45. By accommodating the projection 66 in the recess 45, the movement of the bearing plate 6 in the rotation direction in the outer yoke 42 is restricted, and the position is stabilized. Since the side surface of the support portion 44 provided on the outer yoke 42 and the outer periphery of the bearing plate 6 have the same distance R from the motor axis L, the outer peripheral edge portion of the bearing plate 6 is in contact with the bottom surface and side surface of the support portion 44. Touch. Specifically, as shown in FIG. 6B, the outer peripheral edge of the bottom surface of the bearing plate 6 contacts the bottom surface of the support portion 44, and the outer peripheral surface of the bearing plate 6 contacts the side surface of the support portion 44. Further, at this time, the outer end face 62 of the bearing plate 6 and the end face of the outer yoke 42 have the same height in the motor axis L direction.

(3-2. Mounting the end plate to the outer yoke)
After attaching the bearing plate to the outer yoke 42, the end plate 7 is attached to the end of the outer yoke 42. The end plate 7 has the surface on which the plate spring 72 is cut and raised facing the end of the outer yoke 42. Further, the leaf spring 72 enters the notch 64 and the recess 65 and the accommodating portion 71 is positioned so as to correspond to the projection 63 of the bearing plate 6, and the end plate 7 is brought into contact with the end of the outer yoke 42. Next, the attachment is completed by fixing the contact portion between the end plate 7 and the end of the outer yoke 42 by welding or an adhesive.

  At this time, as shown in FIGS. 6A and 6B, in the bearing plate 6, the three convex portions 63 are respectively accommodated in the three accommodating portions 71 of the end plate 7, and the movement in the horizontal direction is suppressed. . Further, since the outer end face 62 abuts the end plate 7 and is fixed by welding or the like, the bearing plate 6 is also restricted from moving in the motor axis L direction and is fixed to the end portion of the outer yoke 42. . Fixing here means that the position of the bearing plate 6 is maintained relative to the outer yoke 42. That is, adhesion or the like is not essential in this fixed relationship. However, in addition to this fixed relationship, adhesion between the bearing plate 6 and the end plate 7 using an adhesive may be used together.

(3-3. Arrangement of other parts)
As shown in FIG. 1, after the end plate 7 is fixed, 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 hole 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 stepping motor 1 of the present embodiment, the support portion 44 is provided from the end portion of the outer yoke 42 to the pole teeth 43, and the outer periphery and the bottom surface of the bearing plate 6 are placed in the outer yoke 42 so as to contact the support portion 44. By housing, the bearing plate 6 does not protrude greatly in the motor axis L direction, and the entire motor can be reduced in size.

(2) By fixing the end plate 7 to the end of the outer yoke 42, the convex portion 63 of the bearing plate 6 is accommodated in the accommodating portion 71 of the end plate 7 and the outer end face 62 abuts on the end plate 7. Movement in the horizontal direction and the direction of the motor axis L is limited, and the bearing plate 6, the end plate 7 and the outer yoke 42 can be firmly fixed while having a simple structure.

(3) In the present embodiment, the support portion 44 of the outer yoke 42 is formed in a step shape recessed in the radial direction. Further, since the outer circumference of the bearing plate 6 and the side surface of the support portion 44 are both equal in length from the motor axis L, the bearing plate 6 is only accommodated inside the outer yoke 42, so that the bottom surface and the outer circumference portion of the bearing plate 6 are accommodated. Is brought into contact with the bottom and side surfaces of the support portion 44 to maintain the position. Further, by inserting the protrusion 66 into the recess 45 of the outer yoke 42 in the bearing plate 6, the movement of the bearing plate 6 in the rotation direction within the outer yoke 42 is restricted, and the position is stabilized. With such a configuration, the bearing plate 6 can be attached to the outer yoke 42 without requiring a process such as press-fitting, and at the same time it can be aligned with the rotary shaft 21, so that work efficiency and production efficiency can be improved. .

(5. Other embodiments)
The present invention is not limited to the above embodiment, and includes other embodiments as described below.
(1) In this embodiment, the stepped support portion 44 having the bottom surface and the side surface is provided on the outer yoke 42, but the present invention is not limited to such a shape. For example, as shown in FIG. 6C, the outer yoke 42 may be inclined from the end portion to the pole teeth 43. In this case, an inclination may be provided on the outer peripheral portion of the bearing plate 6 so as to correspond to the inclination of the support portion 44.

(2) The end plate 7 may be further provided with a metal cover 73 as shown in FIG. As shown in FIG. 7B, the end plate 7 and the bearing plate 6 can be protected by covering the cover 73. The cover 73 is overlapped on the end surface of the end plate 7 and fixed by welding or an adhesive.

(3) In the present embodiment, the bearing plate 6 is provided with the three convex portions 63, but the number is not limited to this. One or two convex portions 63 of the bearing plate 6 may be provided, or four or more convex portions 63 may be provided. In this case, the accommodating portions 71 of the end plate 7 may be provided in the same number or more as the convex portions 63.

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

(5) Although the bearing plate 6 which is a sliding bearing formed by resin molding is used as a bearing that rotatably supports the rotating shaft 21, a ball bearing, a roller bearing, or the like may be used.

(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 Electrode 44 Support part 45 Recess 5 Coil bobbin 51 Terminal pin 6 Bearing plate 61 Bearing hole 62 Outer end face 63 Protrusion 64 Cutting Notch portion 65 Recess portion 66 Protrusion portion 7 End plate 71 Housing portion 72 Leaf spring 73 Cover 8 Motor mounting plate 81 Base end side vertical plate 81a Hole portion 82 Flat plate 82a Hole portion 83 Front end side vertical plate 9 Output end side bearing plate L Motor axis

Claims (4)

A rotating shaft with a magnet fixed around the shaft;
A cylindrical yoke surrounding the magnet;
A bearing plate disposed at an end of the yoke and supporting one end of the rotating shaft;
An end plate disposed on the outer end surface of the bearing plate opposite to the yoke, and fixing the bearing plate to the yoke;
A plurality of pole teeth are provided at the end of the yoke, and a support portion for supporting the bearing plate is formed on a surface of the pole teeth facing the magnet, and the bearing plate is provided on the support portion of the yoke. Arranged in the yoke in contact with the outer periphery,
Stepping motor characterized by The support part is formed in a step shape;
The stepping motor according to claim 1. A convex portion is provided on the outer end surface of the bearing plate,
On the surface of the end plate facing the bearing plate, a storage portion for storing the convex portion of the bearing plate is formed.
The stepping motor according to claim 1, wherein: In the bearing plate,
A bearing hole penetrating in the plate thickness direction and supporting the rotating shaft is penetrated,
A recess having a larger diameter than the bearing hole is formed on the outer end surface, and a notch is formed by cutting from the recess to the outer peripheral surface of the bearing plate.
The end plate is provided with a leaf spring that is cut and raised from the outer peripheral portion through the cutout portion toward the recess,
The rotating shaft is inserted through the bearing hole and abuts against a leaf spring, and is urged by the leaf spring;
The stepping motor according to any one of claims 1 to 3, wherein: