JP2009089489A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor achieved in further space saving while maintaining an output. <P>SOLUTION: A first case part 2A of a case 2 used in the stepping motor 1 has: a side plate 30 extending in parallel with a rotating axial line L; a first end plate 31 extending orthogonally with respect to the rotating axial line L at the one-end side of the side plate 30 in the direction of the rotating axial line L; and a second end plate 32 extending in parallel with the first end plate 31 on the other-end side of the side plate 30 in the direction of the rotating axial line L. A second case part 2B has: a side plate 40 extending in parallel with the rotating axial line L, a third end plate 41 extending orthogonally with respect to the rotating axial line L at the one-end side of the side plate 40 in the direction of the rotating axial line L; and a fourth end plate 42 extending in parallel with the third end plate 31 on the other-end side of the side plate 40 in the direction of the rotating axial line L. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a PM (permanent magnet) type stepping motor used for driving a lens of a camera, driving a pickup lens of a media-related device, and the like.

  Conventionally, as a technology in such a field, there is JP-A-2003-9499. In the stepping motor described in this publication, a north pole and a south pole are alternately magnetized on the outer periphery of a shaft (rotary shaft) supported by a bearing fixed to a cylindrical casing (case). A rotor and a pair of stators arranged so as to sandwich the rotor in the axial direction of the shaft are provided. Each stator has a bobbin arranged side by side so as to sandwich the magnet in the axial direction of the shaft, and each bobbin is radially sandwiched between the pole tooth row of the inner yoke and the pole tooth row of the outer yoke. It is comprised with the yoke to accommodate. A stepping motor in which a rotor and a stator have an arrangement relationship is suitable for driving a lens of a camera that requires a desired torque, and enables a reduction in the diameter of the casing.

JP 2003-9499 A JP 2002-142431 A

  The conventional stepping motor described above has an advantage that the diameter of the cylindrical casing can be reduced because the rotor and the stator are arranged in parallel in the rotation axis direction. However, devices such as digital cameras have been developed for multi-functionality and thinning. Under such circumstances, stepping motors are required to further save space. And, as a stepping motor of a type that saves space, there is a case where the casing (case) has an oval cross section, but this type of stepping motor has a smaller inner yoke and outer yoke. There was a problem that the output of the motor became small.

  An object of the present invention is to provide a stepping motor capable of further saving space while maintaining output.

A stepping motor according to the present invention is a stepping motor having a rotor fixed to a rotation shaft, a pair of stators arranged in parallel in the rotation axis direction outside the rotor, and a case for housing the rotor and the stator.
The case includes a side plate extending parallel to the rotation axis, a first end plate extending perpendicular to the rotation axis on one end side of the side plate in the rotation axis direction, and the other end side of the side plate in the rotation axis direction. And a first case portion having a second end plate extending in parallel with the first end plate,
The first case portion is formed in a U shape in a cross section along the rotation axis.

  This stepping motor is a type in which rotors fixed to a rotating shaft are arranged in parallel so as to sandwich the rotating shaft in the direction of the rotating shaft, and was developed for the purpose of downsizing the case. The first case portion of the case employed in this type of stepping motor includes a side plate extending parallel to the rotation axis, and a first plate extending perpendicular to the rotation axis at both ends of the side plate in the rotation axis direction. The first end plate and the second end plate are formed in a U shape in a cross section along the rotation axis, and the rotor and the stator are sandwiched between the first end plate and the second end plate in the rotation axis direction. . Therefore, in the radial direction of the stepping motor, the stator can be enlarged to the inner wall surface of the side plate, and at the same time, the stator 7 can be exposed. The presence of this exposed part in the case makes it possible to save space by the thickness of the case compared to conventional stepping motors that employ a cylindrical case. In a small stepping motor, the ratio of the case thickness in the radial dimension is large, and the case thickness has a great influence on the downsizing of the stepping motor. Therefore, even if the stepping motor has the same stator diameter and the same output magnetic circuit, the stepping motor according to the present invention can save space. Further, when the side plate is formed in a flat plate shape and used as a seat plate, a stepping motor that is difficult to roll is obtained. Further, the side plate can be formed in a circular arc shape for further space saving.

The case also includes another side plate extending in parallel to the side plate, a third end plate extending perpendicular to the rotation axis on one end side of the other side plate in the rotation axis direction, and the rotation axis direction. A second case portion having a fourth end plate extending in parallel to the third end plate on the other end side of the other side plate;
The second case portion is formed in a U shape in a cross section along the rotation axis, and is joined in a state where the first end plate and the third end plate are overlapped, and the second end plate and the fourth end plate are joined together. It is preferable that the end plates are joined together in an overlapped state.
In this case, the first end plate of the first case portion and the third end plate of the second case portion are joined in an overlapped state, and the second end plate and the second end plate of the first case portion are joined together. The fourth end plate of the case part is joined in a state of being overlapped. Therefore, since the end plates are in a stacked state in the rotation axis direction, the case can be strengthened.

Further, at least one of the first and second end plates is formed with a mouth opening, and at least one of the third and fourth end plates is formed with a mouth opening. Is preferred.
Thus, the assembling workability of the case is improved by forming the mouth opening in the end plate. In particular, if a mouth-opening is formed in all of the first to fourth end plates, the case can be assembled in a direction orthogonal to the rotation axis, which makes the case assembling work extremely easy.

Further, it is preferable that an opening for exposing a terminal connected to the coil is formed in at least one of the side plate of the first case portion and the side plate of the second case portion.
If an opening is provided in at least one of the side plate of the first case and the side plate of the second case, the terminal can be exposed. And the base of a terminal (block part) can also be exposed by enlarging an opening part. Furthermore, in the case where openings are allowed in both the side plate of the first case part and the side plate of the second case part, it is possible to share components and reduce the weight of the case. Then, by making the first case part and the second case part the same part, the manufacturing cost can be reduced and the part management becomes easy.

  According to the present invention, further space saving can be achieved while maintaining the output.

Hereinafter, preferred embodiments of a stepping motor according to the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 and 2, the case 2 of the stepping motor 1 is divided into two parts by a first case part 2A and a second case part 2B made of a non-magnetic material (for example, stainless steel). . The width and height of the case 2 is about 6 mm or less and the total length is about 12 mm. The stepping motor 1 itself is downsized to drive a lens of a camera and a pickup lens of a media-related device. Used.

  This stepping motor 1 has a rotor 5 made of a permanent magnet in which N poles and S poles are alternately magnetized at equal intervals in the circumferential direction, and the rotor 5 is fixed to a rotating shaft 3. A pair of stators 7 </ b> A and 7 </ b> B are arranged in parallel in the direction of the rotational axis L in front of and behind the rotor 5, that is, outside the rotor 5 in the direction of the rotational axis L of the rotational shaft 3.

  The front stator 7A includes a coil 9A wound around a resin bobbin 20A and a yoke 11A that accommodates the coil 9A. The yoke 11A has an outer yoke 13A and an inner yoke 15A made of iron, and the outer yoke 13A and the inner yoke 15A are coupled in a magnetic circuit manner via a sleeve 28 for rotatably supporting the rotary shaft 3. The end portion of the sleeve 28 is provided with a bearing portion 28b formed in a flange shape at the end portion of the sleeve main body 28a. The outer yoke 13A has four magnetic pole teeth 17A having a comb shape extending from the edge of the base portion 14A of the donut plate shape in the rotation axis L direction, and the inner yoke 15A is the base portion 16A of the donut plate shape. The four magnetic pole teeth 19A extending in the direction of the rotation axis L from the edge of the magnetic poles and having a comb shape are provided.

  The base portion 14A of the outer yoke 13A and the base portion 16A of the inner yoke 15A are respectively arranged in parallel to the outer side and the inner side of the coil 9A in the rotation axis L direction, and the magnetic pole teeth 17A and the magnetic pole teeth 19A They are alternately arranged on substantially the same circumference so as to surround them. In the motor 1 having such a configuration, the case 9 can be made small in the radial direction of the stepping motor 1 because the coil 9A and the rotor 5 are arranged in parallel in the rotation axis L direction.

  Further, two terminals 23A are provided in the resin block portion 22A of the terminal unit 21A exposed from the case 2, and the windings 9a protruding from the coils 9A are wound around the terminals 23A, respectively. The winding 9a is soldered. The coil 9A is held by a resin bobbin 20A formed integrally with the block portion 22A of the terminal unit 21A. Therefore, current can be supplied from the external power source to the coil 9A via the terminal 23A of the terminal unit 21A.

  Next, since the configuration of the stator 7B is the same as that of the stator 7A, the stator 7B will be briefly described. The rear stator 7B includes a coil 9B and a yoke 11B that houses the coil 9B. The yoke 11B has an outer yoke 13B and an inner yoke 15B made of iron. The outer yoke 13B and the inner yoke 15B are magnetically coupled via a sleeve 29, and a bearing portion 29b formed in a flange shape at the end of the sleeve body 29a is provided at the end of the sleeve 29. It has been. The outer yoke 13B and the inner yoke 15B include four magnetic pole teeth 17B and four magnetic pole teeth 19B that extend in the direction of the rotation axis L from the edges of the base portions 14B and 16B of the donut plate shape and form a comb shape. Have.

  Further, two terminals 23B are provided in the resin block portion 22B of the terminal unit 21B exposed from the case 2, and a winding 9b protruding from the coil 9B is fixed to each terminal 23B. The coil 9B is held by a resin bobbin 20B formed integrally with the block portion 22B of the terminal unit 21B.

  In the pair of front and rear stators 7A and 7B configured as described above, the magnetic pole teeth 17A, 19A, 17B, and 19B are arranged to face the outer peripheral surface of the rotor 5, and the magnetic pole teeth 17A of the stator 7A and the magnetic poles of the stator 7B are arranged. The teeth 17B do not coincide with the rotation axis L direction, and are shifted by a predetermined angle. The magnetic pole teeth 19A of the stator 7A and the magnetic pole teeth 19B of the stator 7B are also shifted by a predetermined angle. Then, by sequentially switching the direction of the current flowing through the coils 9A and 9B via the terminals 23A and 23B of the terminal units 21A and 21B, the rotor 5 is rotated in a step shape, and accordingly, the rotary shaft 3 is also rotated in a step shape. To do.

  Further, as shown in FIGS. 1 to 5, the nonmagnetic case 2 for housing the pair of stators 7A and 7B and the rotor 5 is formed by drawing, and the first case portion 2A and the second case Divided into two parts by the part 2B.

  The first case portion 2A includes a flat rectangular side plate 30 that extends parallel to the rotation axis L, and a first extension that is orthogonal to the rotation axis L at one end of the side plate 30 in the direction of the rotation axis L. 1 end plate 31 and a second end plate 32 extending in parallel to the first end plate 31 on the other end side of the side plate 30 in the direction of the rotation axis L, and the first case portion 2A includes The rotor 5 and the yokes of the stators 7A and 7B are formed between the first end plate 31 and the second end plate 32 in the direction of the rotation axis L. 11A, 11B and coils 9A, 9B are arranged.

  Further, the side plate 30 is formed with a rectangular opening 33 for exposing the block portion 22A forming the base of the terminal 23A and the block portion 22B forming the base of the terminal 23B. The opening 33 can reduce the weight of the first case portion 2A. Further, by making the circumferential shape when the block portion 22A and the block portion 22B are combined and the outer shape of the rectangular opening portion 33 substantially the same, the block portions 22A and 22B are prevented from rattling, and the opening portion 33 is It is also useful for positioning the block portion 22A and the block portion 22B.

  The first and second end plates 31 and 32 are formed with mouth-shaped openings 34 and 35 for receiving the bearing portions 28b and 29b of the sleeves 28 and 29, respectively. Each opening 34, 35 is formed between the first finger portions 31a, 32a and the second finger portions 31b, 32b, and extends in a direction orthogonal to the rotation axis L. The same.

  Furthermore, the opening portions 34 and 35 are curved portions 34a, having a radius of curvature equal to the diameter of the bearing portions 28b and 29b between the first finger portions 31a and 32a and the second finger portions 31b and 32b. 35a. In this way, when the first and second end plates 31 and 32 are formed with the opening portions 34 and 35 having the mouth opening shape, the first finger portions 31a and 32a and the second finger portions 31b and 32b are used as bearing portions 28b. 29b can be assembled in the direction orthogonal to the rotation axis L so that the assembling work of the first case 2A becomes extremely easy.

  Further, reinforcing ribs 36 and 37 extending in the direction of the rotation axis L are integrally formed on both sides of the side plate 30 so as to connect the first end plate 31 and the second end plate 32. . Thereby, the strength of the first case portion 2A is increased, and the case 2 is resistant to vibration. Furthermore, as a measure for increasing the strength, triangular pyramid-shaped reinforcing ribs 38 are provided at the boundary portion between the side plate 30 and the first end plate 31 and at the boundary portion between the side plate 30 and the second end plate 32.

  Next, the second case portion 2B will be described. In order to share parts, the same case as the first case portion 2A described above is used for the second case portion 2B. The second case portion 2B includes a side plate 40 having the same shape as the side plate 30, a third side plate 41 having the same shape as the first end plate 31, and a fourth side plate having the same shape as the second side plate 32. 42, the other components of the second case portion 2B are denoted by the same reference numerals as those of the first case portion 2A, and the description thereof is omitted. Thus, by making the first case portion 2A and the second case portion 2B the same component, the case 2 can be reduced in weight and the manufacturing cost can be reduced, and component management is facilitated.

  In assembling the case 2, the first end plate 31 and the third end plate 41 are joined together by welding A in a state of being overlaid, and the second end plate 32 and the fourth end plate 42 are overlaid. In this state, they are joined by welding (not shown) (see FIG. 3). Therefore, in the direction of the rotation axis L, the end plates on both sides of the case 2 are in a stacked state, so that the case 2 can be made strong. At this time, the bearing portion 28b is sandwiched between the curved portion 34a of the end plate 31 of the first case portion 2A and the curved portion 34a of the end plate 41 of the second case portion (see FIG. 3). Similarly, the bearing portion 29b is sandwiched between the curved portion 35a of the end plate 32 of the first case portion 2A and the curved portion 35a of the end plate 42 of the second case portion. In order to facilitate the construction of each weld A, in the first to fourth end plates 31, 32, 41, 42, the first finger portions 31a, 32a and the second finger portions 31b, 32b are It gets thinner as you go to the tip.

  By adopting the above-described first and second case portions 2A, 2B in the stepping motor 1, the stators 7A, 7B can be enlarged to the inner wall surface of the side plates 30, 40 in the radial direction of the stepping motor 1. At the same time, the stators 7A and 7B can be exposed. The presence of this exposed part in the case 2 can save space by the thickness of the case compared to a conventional stepping motor that employs a cylindrical case. In the case of the small stepping motor, the thickness of the case occupies a large proportion in the radial dimension, and the thickness of the case greatly affects the miniaturization of the stepping motor. Therefore, even if the stepping motor has the same stator diameter and the same output magnetic circuit, the stepping motor 1 according to the present embodiment can save space. Further, since the side plate 40 has a flat plate shape, when the side plate 40 is used as a seat plate, the stepping motor 1 is difficult to roll.

  It goes without saying that the present invention is not limited to the embodiment described above. For example, the intended purpose can be achieved even if the case 2 is constituted only by the first case portion 2A. In order to further reduce the space, the side plates 30 and 40 may be arcuate in section along the outer shape of the stators 7A and 7B. In the first case portion 2A, one of the mouth opening 34, 35 may be a circular opening (not shown), and in the second case 2B, the mouth opening 34, One of 35 may be a circular opening (not shown). Further, the opening 33 may not be formed in the side plate 40 of the second case portion 2B. The side plate of the other case portion may be superimposed on both ends of the side plate of one case portion in the direction of the rotation axis L.

1 is an exploded perspective view showing an embodiment of a stepping motor according to the present invention. It is a front view of the stepping motor shown in FIG. It is a side view of the stepping motor shown in FIG. It is sectional drawing which follows the IV-IV line of FIG. (a) is a plan view of the case, (b) is a front view of the case, and (c) is a side view of the case.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Stepping motor, 2 ... Case, 2A ... 1st case part, 2B ... 2nd case part, 3 ... Rotating shaft, 5 ... Rotor, 7A, 7B ... Stator, 30, 40 ... Side plate, 31 ... 1st End plate, 32 ... second end plate, 33, 34, 35 ... opening, 41 ... third end plate, 42 ... fourth end plate, L ... rotation axis.

Claims (4)

In a stepping motor having a rotor fixed to a rotation shaft, a pair of stators arranged in parallel in the rotation axis direction outside the rotor, and a case housing the rotor and the stator,
The case is
A side plate extending parallel to the rotational axis;
A first end plate extending perpendicularly to the rotation axis on one end side of the side plate in the rotation axis direction;
A first case portion having a second end plate extending in parallel to the first end plate on the other end side of the side plate in the rotation axis direction;
The stepping motor according to claim 1, wherein the first case portion is formed in a U shape in a cross section along the rotation axis. The case is
Another side plate extending parallel to the side plate;
A third end plate extending perpendicularly to the rotation axis on one end side of the other side plate in the rotation axis direction;
A second case portion having a fourth end plate extending in parallel to the third end plate on the other end side of the other side plate in the rotation axis direction;
The second case portion is formed in a U shape in a cross section along the rotation axis,
The first end plate and the third end plate are joined in an overlapped state, and the second end plate and the fourth end plate are joined in an overlapped state. The stepping motor according to claim 1.   At least one of the first and second end plates is formed with a mouth opening, and at least one of the third and fourth end plates is formed with a mouth opening. The stepping motor according to claim 2. The opening for exposing the terminal connected to the coil is formed in at least one of the side plate of the first case portion and the side plate of the second case portion. The stepping motor according to 3.

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