JP2005304195A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high output stepping motor more inexpensively without the sacrifice of miniaturization. <P>SOLUTION: In an inner yoke/shaft type CAM, a magnet has a number of poles equal to a multiple of 4 and the number of outer magnetic poles is decimated to one half of a normal number, i.e. to a quarter of the number of poles. Outer magnetic poles of a first stator and a second stator are arranged to be overlapped with each other in the axial direction. By such an arrangement, the magnets are utilized effectively while suppressing crosstalk. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of a cylindrical stepping motor.

  There has been proposed a stepping motor in which the diameter around the rotation axis is reduced and the output is increased (for example, Patent Document 1). FIG. 6 shows an exploded perspective view of the stepping motor, and FIG. 7 shows a sectional view of the shaft center after the stepping motor is assembled.

  In these figures, 201 is a cylindrical rotor composed of permanent magnets (magnets) divided into four in the circumferential direction and alternately magnetized to different poles, and 202 is arranged adjacent to the axial direction of the rotor 201. Similarly, the first coil 203 is a second coil disposed adjacent to the axial direction of the rotor 201, and 204 is a first stator made of a soft magnetic material excited by the first coil 202, 205. Is a second stator made of a soft magnetic material excited by the second coil 203.

  The first stator 204 includes first outer magnetic pole portions 204A and 204B that face the outer peripheral surface of the rotor 201 with a gap, and a first inner magnetic pole portion that faces the inner peripheral surface of the rotor 201 with a gap. 204C and 204D, and the second stator 205 has a second outer magnetic pole portion 205A, 205B facing the outer circumferential surface of the rotor 201 with a gap and a gap in the inner circumferential surface of the rotor 201. Opposing second inner magnetic pole portions 205C and 205D are provided. Reference numeral 206 denotes an output shaft, to which the rotor 201 is fixed, and is rotatably held by the bearing portion 204E of the first stator 204 and the bearing portion 205E of the second stator 205. Reference numeral 207 denotes a connecting ring made of a non-magnetic material, which holds the first stator 204 and the second stator 205 at a predetermined interval.

  In the above configuration, the energization direction to the first coil 202 and the second coil 203 is switched, and the first outer magnetic pole portions 204A and 204B, the first inner magnetic pole portions 204C and 204D, and the second outer magnetic pole portion 205A. , 205B and the second inner magnetic pole portions 205C, 205D are switched in polarity, and the rotor 201 is rotated.

  In this stepping motor, the magnetic flux generated by energizing the coil flows from the outer magnetic pole part to the opposing inner magnetic pole part, or from the inner magnetic pole part to the opposing outer magnetic pole part, and between the outer magnetic pole part and the inner magnetic pole part. It works efficiently on the magnet that forms the rotor located in the center. Further, since the distance between the outer magnetic pole part and the inner magnetic pole part can be made about the thickness of the cylindrical magnet, the resistance of the magnetic circuit composed of the outer magnetic pole part and the inner magnetic pole part can be reduced. . The smaller the resistance of the magnetic circuit, the more magnetic flux can be generated with less current, leading to improved output.

As a further improvement of the stepping motor, the inner magnetic pole portion is formed in a cylindrical shape, the output shaft inserted into the inner diameter portion of the inner magnetic pole portion is formed of a soft magnetic material, and the stator (inner magnetic pole portion and A bearing which is attached to an outer magnetic pole portion and holds the output shaft rotatably is made of a nonmagnetic material (for example, Patent Document 2). According to this proposal, since the output shaft can also be used as a magnetic circuit, the output of the motor is increased.
Japanese Patent Laid-Open No. 09-331666 JP-A-10-229670

  However, in the motor disclosed in Patent Document 2, the magnetic flux generated by energization of the first coil is generated by the second coil, the second outer magnetic pole portion, and the second inner side through the output shaft of the soft magnetic material. Magnetic flux that affects the magnetic pole part, and magnetic flux generated by energizing the second coil affects the first coil, the first outer magnetic pole part, and the first inner magnetic pole part via the output shaft of the soft magnetic material. This makes the rotation unstable.

  Both of the above-mentioned Patent Document 1 and Patent Document 2 require a predetermined distance between the inner diameter of the magnet and the inner magnetic pole portion facing the magnet, and managing this at the time of manufacturing increases the cost. Will be invited. In addition, a cylindrical inner magnetic pole part and an outer magnetic pole part are also required as the shape of the stator, and it is difficult to manufacture them integrally in terms of component manufacture. Further, if they are manufactured separately and then assembled together, the number of parts increases, resulting in an increase in cost.

  Further, when the first outer magnetic pole portion and the second outer magnetic pole portion are close to each other, crosstalk occurs with each other, and rotational accuracy and rotational output are lowered. Therefore, a gap T1 is provided between the first outer magnetic pole part and the second outer magnetic pole part in the axial direction and the parallel direction. In the above document, when the number of magnetized magnetic poles is n poles, the first outer magnetic pole portion and the second outer magnetic pole portion are arranged 180 / n degrees out of phase with each other on the outer peripheral surface of the rotor. Are provided at n / 2 locations at a counter angle of about 360 / n degrees at a pitch of 720 / n degrees with respect to the outer peripheral surface of the rotor, and the second outer magnetic pole part is also provided with a pitch of 720 / n degrees with respect to the outer peripheral surface of the rotor Therefore, if the gap T1 in the direction parallel to the shaft is not provided, the first outer magnetic pole portion and the second outer magnetic pole portion are provided with an opposing angle of about 360 / n degrees. Contact.

  Further, by providing the gap T1, the axial length of the first outer magnetic pole portion facing the magnet rotor becomes (A1-T1) / 2, where A1 is the axial length of the magnet rotor. It cannot be said that the rotor is effectively used, and the output is lowered particularly when the axial dimension of the motor is reduced.

In order to solve the above problems, the invention described in claim 1
A magnet ring made up of a cylindrical permanent magnet with 4 × n equally divided in the circumferential direction and with different poles alternately magnetized, and concentric with the magnet ring and arranged at a position sandwiching the magnet ring in the axial direction The cylindrical first coil and the second coil that are formed are arranged at n equally divided angular positions facing the outer peripheral surface from one end surface of the magnet ring and excited by the first coil. A first outer magnetic pole portion and a second outer magnetic pole which is arranged at n equally divided angular positions facing the outer peripheral surface from the other end face of the magnet ring and is excited by the second coil. And is made of a soft magnetic material, is fixed to the inner diameter portion of the magnet ring, and is opposed to at least the first outer magnetic pole portion and the second outer magnetic pole portion in the axial range. And the first outer magnetic pole portion and the second outer magnetic pole portion have a relative position (112.) with respect to the outer peripheral surface of the magnet ring. The stepping motor is characterized in that it is arranged so as to be shifted by 5 / n) degrees and at least partially overlap in the axial direction of the magnet ring.

  According to the present invention, it is possible to provide a high-power stepping motor at a lower cost without impairing downsizing.

  As shown in Example 1 and Example 2 below.

  1 to 4 are diagrams according to Embodiment 1 of the present invention, FIG. 1 is an exploded perspective view of a stepping motor, and FIG. 2 is an axial sectional view after assembly of the stepping motor of FIG. 3 is a cross-sectional view at a position BB in FIG. FIG. 3 is a cross-sectional view perpendicular to the shaft after assembly of the stepping motor of FIG. 1, and is a cross-sectional view at the AA position in FIG. FIG. 4 is a cross-sectional view showing the operating state.

  In these drawings, reference numeral 1 denotes a cylindrical magnet ring constituting the rotor. The magnet ring 1 as the rotor is divided into 4 × n (an integer multiple of 4 at an equal interval in the circumferential direction). n is an integer, and in this embodiment, n = 4, that is, the number of divisions 16), and magnetized portions 1A, 1B, 1C, 1D, 1E, 1F, 1G, in which S poles and N poles are alternately magnetized, 1H, 1I, 1J, 1K, 1L, 1M, 1N, 1P, 1Q. The outer peripheral surfaces of the magnetized portions 1A, 1C, 1E, 1G, 1I, 1K, 1M, and 1P are S poles, and the outer peripheral surfaces of 1B, 1D, 1F, 1H, 1J, 1L, 1N, and 1Q are N poles. . The magnet ring 1 is made of a plastic magnet formed by injection molding, and since it has a simple shape, it can be easily made small and thin. In addition, no cracks occur even when assembled by press fitting. 2 is a cylindrical first coil, and 3 is a cylindrical second coil, both of which have a central portion coinciding with the central portion of the magnet ring 1 and are aligned in the axial direction. It is arranged at a position sandwiching the ring 1. The outer diameters of the first and second coils 2 and 3 are substantially equal to the outer diameter of the magnet ring 1.

  8 is a first stator and 9 is a second stator, both of which are made of a soft magnetic material, and have a cylindrical outer cylinder portion. The first stator 8 is formed with comb-shaped first outer magnetic pole portions 8A, 8B, 8C, and 8D that face the outer peripheral surface of the magnet ring 1 with a predetermined gap. The first outer magnetic pole portions 8A, 8B, 8C, and 8D are divided into a plurality of portions in the circumferential direction by cutting out the tip of the outer cylindrical portion of the cylindrical first stator 8, each of which is one of the magnet rings 1. Comb-shaped magnetic poles extending in the axial direction from the end face of the first electrode are formed. The first outer magnetic pole portions 8A, 8B, 8C, and 8D are formed to be shifted by 360 / n degrees, that is, 90 degrees. The second stator 9 is also formed with comb-shaped second outer magnetic pole portions 9A, 9B, 9C, 9D that face the outer peripheral surface of the magnet ring 1 with a predetermined gap. The second outer magnetic pole portions 9A, 9B, 9C, and 9D are divided into a plurality of portions in the circumferential direction by cutting out the tip of the outer cylindrical portion of the cylindrical second stator 9, and each of them is divided into the first stator 8. A comb-shaped magnetic pole extending in the axial direction from the other end face of the magnet ring opposite to the case is formed. The second outer magnetic pole portions 9A, 9B, 9C, and 9D are also formed to be shifted by 360 / n degrees, that is, 90 degrees.

  The first outer magnetic pole portions 8A, 8B, 8C, 8D of the stator 8 and the second outer magnetic pole portions 9A, 9B, 9C, 9D of the second stator 9 are both in a direction parallel to the notch hole and the axis. It is composed of extending teeth. With this configuration, the magnetic pole portion can be formed while minimizing the diameter of the stepping motor. In other words, if the outer magnetic pole portion is formed with irregularities extending in the radial direction, the diameter of the motor will be increased by that amount. In this embodiment, the outer magnetic pole portion is formed by teeth extending in a direction parallel to the notch hole and the axis. Since the magnetic pole portion is configured, the diameter of the motor can be minimized.

  The first stator 8 is excited by the first coil 2, and the second stator 9 is excited by the second coil 3.

  The first outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 and the second outer magnetic pole portions 9A, 9B, 9C, 9D of the second stator 9 have the same shape and are mutually connected. The comb-shaped magnetic pole portions are arranged so that the tips thereof face each other and overlap with each other on the outer peripheral surface of the magnet ring with respect to the position parallel to the axis of the magnet ring. The first outer magnetic pole portions 8A, 8B, 8C, and 8D and the second outer magnetic pole portions 9A, 9B, 9C, and 9D of the second stator 9 are the same as those of the magnet ring 1 in all the axial lengths of the magnet ring 1. Opposite the outer peripheral surface.

  When the length of the magnet ring 1 is indicated by A1, the number of first outer magnetic poles is 4 × n in the conventional example compared to the conventional example (Patent Document 1 Japanese Patent Laid-Open No. 09-331666). Is 2 × n locations and facing length (A1−T1) / 2, so that the total facing amount is n × (A1−T1), whereas in the present invention, the total facing amount becomes n × A1. Thereby, a magnet can be used effectively and it can be set as a motor with big output.

  The first stator 8 and the second stator 9 are arranged such that the phases of the comb-shaped magnetic pole portions are shifted by (112.5 / n) degrees, that is, 28.125 °. In FIG. 3, the angle is represented by C.

  The first stator 8 and the second stator 9 have an angular range per tooth (denoted by D in FIG. 3) facing the magnet ring of the comb-shaped magnetic pole portion of 360 / (4 × n ) Degrees or less, that is, 22.5 degrees or less, the center of the comb teeth that are the outer magnetic pole portions of the first stator 8 and the center of the comb teeth that are the outer magnetic pole portions of the second stator 9 are shifted by 28.125 degrees. Therefore, the first outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 and the second outer magnetic pole portions 9A, 9B, 9C, 9D of the second stator 9 have the same shape. Thus, even if they are arranged so that the tips of the comb-shaped magnetic pole portions face each other and overlap each other on the outer peripheral surface of the magnet ring with respect to the position parallel to the axis of the magnet ring, they are separated from each other. For this reason, since the first outer magnetic pole part and the second outer magnetic pole part do not cause crosstalk with each other, the rotation accuracy and the rotation output do not deteriorate.

  Reference numeral 10 denotes a rotating shaft made of a soft magnetic material, which is fixed to the inner diameter portion of the magnet ring 1. The rotating shaft 10 has an outer diameter at a position where the magnet ring 1 is sandwiched in the axial range facing the first outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 facing the magnet ring 1. An inner magnetic pole portion 10A having a dimension D1 is formed. The second outer magnetic pole portions outer magnetic pole portions 9A, 9B, 9C, 9D overlap with respect to the positions of the first outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 in the direction parallel to the axis of the magnet ring. Therefore, the inner magnetic pole portion 10A is also opposed to the second outer magnetic pole portion outer magnetic pole portions 9A, 9B, 9C, and 9D.

  A part 10C of the rotating shaft 10 is inserted into the inner diameter part of the first coil 2, and the first inner magnetic pole part 10A is connected to the first outer magnetic pole parts 8A, 8B, 8C, 8D of the first stator 8. Opposite angular ranges are excited by the first coil 2 to the opposite poles of the first stator 8 from the first outer magnetic pole portions 8A, 8B, 8C, 8D. The cross-sectional shape in the direction perpendicular to the axis of the first inner magnetic pole portion 10A of the rotating shaft 10 is a circular shape as shown in FIG. A part 10D of the rotating shaft 10 is inserted into the inner diameter part of the second coil 3, and the inner magnetic pole part 10A faces the second outer magnetic pole parts 9A, 9B, 9C, 9D of the second stator 9. The portion of the angular range is excited by the second coil 3 to a pole opposite to the second outer magnetic pole portions 9A, 9B, 9C, 9D of the second stator 9. The rotary shaft 10 has the magnet ring 1 fixed by an inner magnetic pole portion 10A.

  Since the inner diameter of the magnet ring is filled with the inner magnetic pole portion 10A, the mechanical strength of the magnet is increased, and the inner magnetic pole portion 10A functions as a back metal, so that the permeance coefficient of the magnetic circuit is set high. Even when used in the environment, magnetic deterioration due to demagnetization is reduced. The first stator 8 and the second stator 9 can be configured in a simple shape in which a cutout is provided in the outer cylinder portion in a cup shape, and manufacturing is facilitated and assembly is also facilitated.

  Reference numeral 12 denotes a first bearing made of a nonmagnetic material, which is fixed to the first stator 8 and holds the 10E portion of the rotating shaft 10 rotatably. Reference numeral 13 denotes a second bearing made of a nonmagnetic material, which is fixed to the second stator 9 and holds the 10F portion of the rotating shaft 10 rotatably. Since both the first bearing 12 and the second bearing 13 are made of a nonmagnetic material, they are attracted by the magnetic force generated between the first stator 8 and the rotating shaft 10 and between the second stator 9 and the rotating shaft 10. Can be prevented from being attracted by the magnetic force generated, and the rotational characteristics and durability can be improved.

  The first bearing 12 and the second bearing 13 may be made of a soft magnetic material. In that case, since the magnetic resistance of the magnetic circuit is reduced, the generated torque is increased. Of course, there is a possibility that an adsorption force is generated between the first bearing 12 and the rotary shaft 10 or between the second bearing 13 and the rotary shaft 10 to cause a torque loss due to a frictional force or impair the durability of the sliding surface. However, the surface of the first bearing 12, the rotary shaft 10, and the second bearing 13 is coated with a lubricant, lubricated (fluorine-based lubrication, graphite-based lubrication, or diverted molybdenum-based lubrication), or lubricated (for example, PTFE). (Polytetrafluoroethylene) Electroless nickel plating containing particles, Teflon (registered trademark) lubricated electroless nickel plating, etc.) can be applied to suppress torque loss due to friction of the sliding surface, and durability of the sliding surface Can be prevented, and a motor having a large output torque can be obtained.

  The first coil 2 is disposed between the outer cylindrical portion of the first stator 8 and the rotary shaft 10 and in the vicinity of these connecting portions via the first bearing 12. One end side of the magnet ring 1 is sandwiched between the outer magnetic poles 8A, 8B, 8C, 8D and the inner magnetic pole 10A of the rotating shaft 10. Further, the second coil 3 is arranged between the outer cylindrical portion of the second stator 9 and the rotary shaft 10 and in the vicinity of these connecting portions via the second bearing 13, and the second stator 9 The other end side of the magnet ring 1 is sandwiched between the two outer magnetic poles 9A, 9B, 9C, 9D and the inner magnetic pole 10A of the rotating shaft 10. That is, the outer magnetic poles 8A, 8B, 8C, 8D, 9A, 9B, 9C, 9D are opposed to the outer peripheral surface of the magnet ring 1, and the inner magnetic pole 10A is located on the inner peripheral surface of the magnet ring 1, 8A, 8B, 8C, and 8D are opposed to the inner magnetic pole portion 10A, and similarly, the second outer magnetic pole portions 9A, 9B, 9C, and 9D are opposed to the inner magnetic pole portion 10A.

  Reference numeral 14 denotes a cylindrical connecting ring, and grooves 14A, 14B, 14C, 14D, 14E, 14F, 14G, and 14H are formed inside the connecting ring 14, and the grooves 14A, 14C, 14E, and 14G are mutually connected. The phases of the grooves 14B, 14D, 14F, and 14H are shifted from each other by 360 / n degrees, that is, 90 degrees.

  The first outer magnetic poles 8A, 8B, 8C, 8D of the first stator 8 are fitted into the grooves 14A, 14C, 14E, 14G and fixed with an adhesive or the like, and the grooves 14B, 14D, 14F, 14H have the first The second outer magnetic poles 9A, 9B, 9C, 9D of the second stator 9 are fitted and fixed with an adhesive or the like. The phases of the grooves 14A, 14C, 14E, 14G and the grooves 14B, 14D, 14F, 14H are shifted by (112.5 / n) degrees, that is, 28.125 °. Thus, as described above, the comb-shaped outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 and the comb-shaped outer magnetic pole portions 9A, 9B, 9C, 9D of the second stator 9 are Are arranged and held with a phase shift of (112.5 / n) degrees, that is, 28.125 °.

  By fixing the first stator 8 and the second stator 9 to the connecting ring 14 as described above, the first stator 8 and the second stator 9 are arranged at a desired position and phase. Can do. Further, the connecting ring 14 is made of a nonmagnetic material, and the magnetic circuit between the first stator 8 and the second stator 9 can be divided, and the influence of the mutual magnetic poles is less likely to occur.

  In the first embodiment, the inner diameter portion of the magnet ring 1 is filled with the first inner magnetic pole portion 10A of the rotating shaft 10, so that the magnet ring 1 is magnetized compared to those proposed in Patent Document 1 and Patent Document 2 described above. In addition, since the rotary shaft 10 acts as a so-called back metal that reduces the magnetic resistance between the S pole and N pole appearing on the inner diameter part of the magnet, the permeance coefficient of the magnetic circuit is set high. Therefore, even when used in a high temperature environment, there is little magnetic deterioration due to demagnetization.

  Since the first stator 8 and the second stator 9 have a cup shape and have a simple shape in which a cutout is provided in the outer cylinder portion, the manufacture is easy. If the structure shown in Patent Document 1 or Patent Document 2 described in the prior art is used, each of the first stator and the second stator must integrally form the inner magnetic pole part with the outer magnetic pole part. Manufacture is difficult when the magnetic pole part and the outer magnetic pole part are composed of the same parts. For example, molding with a metal injection mold increases the cost, and it becomes more difficult to manufacture integrally by pressing as the part becomes finer than to manufacture a part constituting the outer magnetic pole part. In addition, when the inner magnetic pole part and the outer magnetic pole part are manufactured separately and then fixed together by caulking, welding, adhesion, or the like, the cost increases. That is, the conventional motor disclosed in Patent Document 1 and Patent Document 2 includes two coils, one magnet ring, one output shaft, and a first stator (parts constituting the outer magnetic pole part and inner magnetic pole part). 2 parts)), 2nd stator (2 parts consisting of the outer magnetic pole part and 2 parts constituting the inner magnetic pole part), and a total of 9 parts of the connecting ring were required. In the example, two coils, one magnet ring, one rotating shaft corresponding to the output shaft, first stator (parts constituting the outer magnetic pole part), second stator (parts constituting the outer magnetic pole part), connecting ring Thus, it can be configured with a total of seven parts, the cost is reduced, and the manufacture is facilitated.

  Furthermore, the motors proposed in Patent Document 1 and Patent Document 2 need to be assembled while maintaining a gap between the outer diameter part of the magnet and the outer magnetic pole part with high accuracy, and are in a position facing the inner diameter part of the magnet. The inner magnetic pole part needs to be arranged with a predetermined gap with respect to the magnet, and this gap cannot be secured due to variations in component accuracy or poor assembly accuracy, and the inner magnetic pole part contacts the magnet. However, in this embodiment, it is only necessary to manage the gap only in the outer diameter portion of the magnet, so that the assembly becomes easy. In addition, since the first inner magnetic pole part and the second inner magnetic pole part are formed of separate parts in the present embodiment, the difference between the first inner magnetic pole part and the second inner magnetic pole part is small and the accuracy is high. It can be a stepping motor.

  Further, in Patent Document 1 and Patent Document 2, the inner magnetic pole portion must be configured not to contact the portion connecting the magnet and the output shaft, whereby the inner magnetic pole portion and the magnet face each other in the axial direction. While the length (L1 in FIG. 7) cannot be made sufficiently long, in this embodiment, as shown by L2 in FIG. 2, the axial length in which the inner magnetic pole portion and the magnet face each other can be easily increased. As a result, the outer magnetic pole part and the magnet can be used effectively, and the output of the motor can be increased.

  Furthermore, when the length of the magnet ring 1 is A1 and the number of poles of the magnet is 4 × n in the conventional example as compared with the conventional example (Patent Document 1, Japanese Patent Application Laid-Open No. 09-331666), the first outer magnetic pole Since the number is 2 × n and the facing length (A1−T1) / 2, the total facing amount is n × (A1−T1), whereas in the present invention, the total facing amount is n × A1 and the total facing amount increases. . Thereby, a magnet can be used effectively and it can be set as a motor with big output.

  FIG. 4 is a cross-sectional view taken along the line AA of FIG. 2, and the rotation driving of the stepping motor will be described using this.

  In the state of FIG. 4A, the first coil 2 and the second coil 3 are energized to excite the outer magnetic pole portions 8A, 8B, 8C, and 8D of the first stator 8 to the N pole, In this state, the outer magnetic pole portions 9A, 9B, 9C, and 9D of the stator 9 are excited to the S pole.

  From the state of FIG. 4A, the first coil 2 and the second coil 3 are energized to excite the outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 to the N pole, and the second When the outer magnetic pole portions 9A, 9B, 9C, and 9D of the stator 9 are excited to the N pole, the magnet ring 1 that is the rotor rotates 11.25 degrees counterclockwise, and the state shown in FIG. Next, the energization to the first coil 2 is reversed, the outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 are excited to the S pole, and the outer magnetic pole portions 9A, 9B of the second stator 9 are excited. , 9C and 9D are excited to the N pole, the magnet ring 1 as a rotor is further rotated 11.25 degrees counterclockwise, and the state shown in FIG. 4C is obtained. Next, the energization of the second coil 3 is reversed, the outer magnetic pole portions 8A, 8B, 8C, 8D of the first stator 8 are excited to the S pole, and the outer magnetic pole portions 9A, 9B of the second stator 9 are excited. , 9C and 9D are excited to the S pole, the magnet ring 1 as a rotor is further rotated 11.25 degrees counterclockwise, and the state shown in FIG.

  Thereafter, by sequentially switching the energization directions to the first coil 2 and the second coil 3 in this way, the magnet ring 1 serving as the rotor rotates sequentially to a position corresponding to the energization phase.

  In the first embodiment, the magnetic flux generated by energizing the coil is directly applied to the magnet in the same manner as that proposed in Patent Document 1 and Patent Document 2, and the stepping motor has a high output. It is supposed to be very small. That is, the diameter of the motor only needs to be large enough to make the magnetic pole of the stator face the magnet diameter, and the length of the stepping motor is equal to the length of the first coil and the second coil. It would be good if it was long enough. For this reason, the size of the stepping motor is determined by the diameter and length of the magnet and coil, and if the diameter and length of the magnet and coil are made extremely small, the stepping motor can be made ultra-small. is there.

  At this time, if the diameter and length of the magnet and the coil are made very small, it becomes difficult to maintain the accuracy as the stepping motor. This is because the magnet is formed in a hollow cylindrical shape, and this hollow cylindrical shape is formed. The problem of accuracy of the stepping motor is solved by a simple structure in which the outer magnetic pole part and the inner magnetic pole part of the first and second stators are opposed to the outer peripheral surface and inner peripheral surface of the formed magnet. Furthermore, as described in the above description, it is possible to achieve high output at low cost.

  FIG. 5 is a cross-sectional view showing a stepping motor according to Embodiment 2 of the present invention. The same components as those in Embodiment 1 are given the same reference numerals, and descriptions thereof are omitted.

  In the figure, reference numeral 15 denotes a first bobbin around which the first coil 2 is wound. The first bobbin 15 is made of a non-magnetic material and a non-conductive material, and prevents the first coil 2 and the first stator 8 from being inadvertently conducted. The first bobbin 15 is fixed to the first stator 8, holds the rotary shaft 10 rotatably through the hole 15A, and performs the same function as the first bearing 12 in the first embodiment. Reference numeral 16 denotes a second bobbin around which the second coil 3 is wound. The second bobbin 16 is also made of a non-magnetic material and non-conductive material so that the second coil 3 and the second stator 9 are not inadvertently conducted. The second bobbin 16 is fixed to the second stator 9, holds the rotary shaft 10 rotatably through the hole 16A, and performs the same function as the second bearing 13 in the first embodiment.

  In the second embodiment, the first coil 2 and the first stator 8 are prevented from being inadvertently connected to each other, and at the same time, the member that prevents the first stator 8 and the rotating shaft 10 from being attracted is a single component, that is, the first bobbin. 15, the assembly is easy, the cost is low, and a stable operation can be performed. Similarly, a member that prevents inadvertent conduction between the second coil 3 and the second stator 9 and at the same time prevents the second stator 9 and the rotating shaft 10 from being adsorbed is constituted by one component, that is, the second bobbin 16. Therefore, it can be set as the structure which can be assembled easily, is cheap, and can perform stable operation.

  According to the first embodiment and the second embodiment described above, the portion of the output shaft 10 that faces the first outer magnetic pole portions 8A, 8B, 8C, and 8D and is fixed to the inner peripheral surface of the magnet ring 1 is used as the inner magnetic pole portion. 10A, the magnetic flux generated by the first coil 2 is fixed to the first outer magnetic pole portions 8A, 8B, 8C, 8D facing the outer peripheral surface of the magnet ring 1 and the inner peripheral surface of the magnet ring 1. Since it passes between the inner magnetic pole part 10 </ b> A of the rotating shaft 10, it effectively acts on the magnet ring 1. At that time, the first inner magnetic pole portion 10A of the rotary shaft 10 facing the inner peripheral surface of the magnet ring 1 does not need to be provided with a gap between the inner peripheral surface of the magnet ring 1. Compared with the cited document 2, the distance between the outer magnetic pole portions 8A, 8B, 8C, 8D and the inner magnetic pole portion 10A can be reduced, the magnetic resistance can be reduced, and the output can be increased.

  The magnetic flux generated by the second coil 2 is applied to the second outer magnetic pole portions 9A, 9B, 9C, 9D facing the outer peripheral surface of the magnet ring 1 and the inner side of the rotary shaft 10 fixed to the inner peripheral surface of the magnet ring 1. Since it passes between the magnetic pole part 10A, it acts on the magnet ring 1 effectively. In that case, since it is not necessary to provide a space | gap between the inner side magnetic pole part 10A of the rotating shaft 10 which opposes the internal peripheral surface of the magnet ring 1 between the internal peripheral surfaces of the magnet ring 1, the said cited reference 1 and cited reference 2 As compared with the above, since the distance between the second outer magnetic pole portions 9A, 9B, 9C, 9D and the inner magnetic pole portion 10A can be reduced and the magnetic resistance can be reduced, the output can be increased.

  Further, since the inner magnetic pole portion 10A is constituted by a single rotating shaft 10, it is compared with the case where the outer magnetic pole portion and the inner magnetic pole portion shown in the cited reference 1 and cited reference 2 are connected or manufactured integrally. Easy to manufacture and low cost.

  Furthermore, since the rotating shaft 10 is fixed to the inner diameter part, the magnet ring 1 is excellent in strength.

  That is, it is possible to provide a motor that has a small number of components and can be configured with easily manufactured components. Further, since the inner magnetic pole portion 10A can be configured to be long, the outer magnetic pole portions 8A, 8B, 8C, 8D, 9A, 9B, 9C, 9D and the magnet ring 1 can be used effectively, and the output of the stepping motor can be increased. Can do. Furthermore, since it is only necessary to manage the gaps between the outer diameter portion of the magnet ring 1 and the outer magnetic pole portions 8A, 8B, 8C, 8D, 9A, 9B, 9C, 9D, assembly is facilitated. Further, since the mechanical strength of the magnet ring 1 is increased and the rotating shaft 10 acts as a back metal, there is little magnetic deterioration of the magnet.

  Further, since the first coil 2 and the second coil 3 have substantially the same diameter as the magnet ring 1 and are disposed at positions sandwiching the magnet ring 1 in the axial direction, the outer diameter of the stepping motor is reduced. doing.

  When the number of magnetic poles of the magnet ring is 4 × n, the comb-shaped outer magnetic pole portion of the first stator is provided at n equally divided angular positions, and the comb-shaped outer magnetic pole of the second stator is provided. The first outer magnetic pole part and the second outer magnetic pole part are displaced by (112.5 / n) degrees relative to the outer peripheral surface of the magnet ring. In addition, when the length of the magnet ring 1 is indicated by A1 by arranging it so that at least a part thereof overlaps with respect to the axial direction of the magnet ring, compared with the case of the conventional example (Patent Document 1, Japanese Patent Laid-Open No. 09-331666). In the conventional example, if the number of poles of the magnet is 4 × n, the number of the first outer magnetic poles is 2 × n and the facing length (A1-T1) / 2, so the total facing amount is n × (A1-T1). In contrast, in the present invention, n × A1. Counter weight increases. Thereby, a magnet can be used effectively and it can be set as a motor with big output. Furthermore, even in this case, since the outer magnetic pole part of the first stator and the outer magnetic pole part of the second stator can be separated from each other, crosstalk can be prevented and a stable performance stepping motor can be obtained.

  The stepping motor of the present invention is useful for small devices such as a photographing device and a mobile phone.

It is a disassembled perspective view which shows the stepping motor which concerns on Example 1 of this invention. It is sectional drawing of the assembly completion state of the stepping motor shown in FIG. It is sectional drawing seen from the direction perpendicular | vertical to the axis | shaft of the rotor of the stepping motor shown in FIG. It is rotation operation explanatory drawing of the rotor of the stepping motor which concerns on Example 1 of this invention. It is a disassembled perspective view which shows the stepping motor which concerns on Example 2 of this invention. It is a disassembled perspective view which shows the conventional stepping motor. It is sectional drawing of the assembly completion state of the stepping motor of FIG.

Explanation of symbols

1 Magnet (Magnet Ring)
2 1st coil 3 2nd coil 8 1st stator 8A, 8B, 8C, 8D 1st outer magnetic pole part 9 2nd stator 9A, 9B, 9C, 9D 2nd outer magnetic pole part 10 Rotating shaft 10A Inner magnetic pole part 12 1st bearing 13 2nd bearing 14 Connecting ring 15 1st bobbin 16 2nd bobbin

Claims (1)

  A magnet ring made up of a cylindrical permanent magnet with 4 × n equally divided in the circumferential direction and with different poles alternately magnetized, and concentric with the magnet ring and arranged at a position sandwiching the magnet ring in the axial direction The cylindrical first coil and the second coil that are formed are arranged at n equally divided angular positions facing the outer peripheral surface from one end surface of the magnet ring and excited by the first coil. A first outer magnetic pole portion and a second outer magnetic pole which is arranged at n equally divided angular positions facing the outer peripheral surface from the other end face of the magnet ring and is excited by the second coil. And is made of a soft magnetic material, is fixed to the inner diameter portion of the magnet ring, and is opposed to at least the first outer magnetic pole portion and the second outer magnetic pole portion in the axial range. And the first outer magnetic pole portion and the second outer magnetic pole portion are positioned relative to the outer peripheral surface of the magnet ring (112. 5 / n) A stepping motor characterized in that the stepping motor is disposed so as to be deviated by at least a part in the axial direction of the magnet ring.

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