JP2015095947A - Pm type stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a claw-pole PM stepping motor in which noise is reduced.SOLUTION: A claw-pole PM stepping motor includes a bobbin 330 having a substantially cylindrical portion around which an exciting coil 340 is wound and having a recess formed in the inner periphery. Two sets of stator are arranged to hold the bobbin 330 therebetween, and the stator has a yoke 310 inside of stator and a yoke 320 outside of stator having a plurality of pole teeth 311, 323 located on the inside of the bobbin 330. The pole teeth 311, 323 are housed in the recess of the bobbin 330, and secured to the bobbin 330 in the recess by means of an adhesive.

Description

  The present invention relates to a PM type stepping motor with reduced noise.

  The claw ball type PM stepping motor is used in many fields because it can be manufactured at low cost. This motor has a simple structure and can be manufactured at a low cost. However, on the other hand, it is necessary to take measures to stabilize the quality and to generate noise. Patent Document 1 discloses a method for suppressing noise in a claw pole type PM stepping motor. Patent Document 1 describes a technique in which a pole tooth storage portion having substantially the same shape as the pole teeth of the stator is formed on the inner peripheral surface of the coil bobbin, and the pole teeth are stored therein to suppress noise.

JP 2003-189484 A

  However, the present inventor has found through experimentation that even if the method described in Patent Document 1 is carried out, a sufficient effect cannot be obtained against noise. Therefore, an object of the present invention is to obtain a claw pole type PM stepping motor capable of reducing noise.

  The invention according to claim 1 is arranged so as to sandwich a bobbin having a substantially cylindrical portion in which an excitation coil is wound and a depression is formed on the inner periphery, each of which is located inside the bobbin. An inner yoke and an outer yoke having a plurality of pole teeth, and two sets of stators in which a plurality of pole teeth of the inner yoke and a plurality of pole teeth of the outer yoke are housed in the recess of the bobbin, a shaft, and the shaft A rotor core fixed to the outer periphery of the rotor core and a magnet disposed on an outer periphery of the rotor core, the rotor being rotatable with respect to the two sets of stators, and an inner peripheral surface of the bobbin in the recess, The PM stepping motor is characterized in that an outer peripheral surface of a plurality of pole teeth of the inner yoke and an outer peripheral surface of the plurality of pole teeth of the outer yoke are bonded with an adhesive. According to the first aspect of the present invention, since the pole teeth are fixed to the bobbin by adhesion, the vibration of the pole teeth is suppressed and the generation of noise is suppressed. In addition, the part of the pole tooth may be accommodated in the depression, or the whole of the pole tooth may be contained.

  According to a second aspect of the present invention, in the first aspect of the invention, the inner peripheral surface of the bobbin in the recess, the outer peripheral surface of the plurality of pole teeth of the inner yoke, and the plurality of pole teeth of the outer yoke. A clearance is provided between the outer peripheral surface and the adhesive is filled in the clearance. According to the second aspect of the present invention, when the intersection of the pole teeth is absorbed and the bobbin has a small inner diameter, it is possible to suppress the occurrence of a problem that the pole teeth are deformed so as to fall down on the shaft side.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, both the axial direction both surfaces of the bobbin and the surface where the inner yoke and the outer yoke contact are fixed by adhesion. . According to the invention described in claim 3, the generation of noise is further suppressed.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the opposing surfaces of the inner yokes of the two sets of stators are fixed by adhesion. . According to invention of Claim 4, generation | occurrence | production of a vibration can be suppressed compared with the case where inner yokes are not fixed with an adhesive agent.

  According to the present invention, a claw pole type PM stepping motor with reduced noise can be obtained.

It is a disassembled perspective view of embodiment. It is a sectional side view of an embodiment. It is a sectional side view of one stator. It is a sectional side view of a bobbin. FIG. 3 is a diagram illustrating a bonded portion between a yoke and a bobbin in the first embodiment. FIG. 6 is a diagram illustrating a bonded portion between a yoke and a bobbin in the second embodiment. It is a figure which shows the adhesion part of the yoke and bobbin in a comparative example. It is the data and graph which measured the noise value.

(Embodiment)
1 and 2 show a claw pole type PM stepping motor 100 utilizing the present invention. The PM type stepping motor 100 includes a stator 400, a rotor 500, a front plate 600 attached to the front surface of the stator 400, and an end plate 700 attached to the back surface of the stator 400.

  Stator 400 includes A-phase stator 200 and B-phase stator 300. The A-phase stator 200 and the B-phase stator 300 are the same, and the stators 400 are configured by joining those inverted in the axial direction back to back.

  Since the A-phase stator 200 and the B-phase stator 300 are the same, the B-phase stator 300 will be described below. FIG. 3 is a side sectional view of the B-phase stator 300 cut in the axial direction. The B-phase stator 300 has a stator inner yoke 310 and a stator outer yoke 320 constituting a stator yoke, and further has a bobbin 330.

  The stator inner yoke 310 has a flat annular shape made of a soft magnetic material such as an electromagnetic steel plate, and has a plurality of pole teeth 311 protruding in the axial direction from the inner edge thereof. The stator outer yoke 320 is made of a soft magnetic material such as an electromagnetic steel plate, and includes a cylindrical portion 321, a flat annular shape annular portion 322 on the other end side of the cylindrical portion 321, and an inner edge of the annular portion 322. It has a plurality of pole teeth 323 protruding in the axial direction.

  The stator inner yoke 310 and the stator outer yoke 320 are coupled in a state where the outer edge of the stator inner yoke 310 is in contact with the edge of the cylindrical portion 321 of the stator outer yoke 320. In this state, the pole teeth 311 and 323 are in a positional relationship in which they are meshed with each other with gaps alternately in the circumferential direction. A bobbin 330 around which an exciting coil 340 (see FIG. 2) is wound is housed in a donut-shaped space between the pole teeth 311 and 323 and the cylindrical portion 321. On the end surface of the bobbin 330 in the axial direction, a convex portion that fits into a hole provided in the annular portion 322 is provided. The bobbin 330 is positioned by fitting the convex portion into the hole.

  FIG. 4 is a side sectional view of the bobbin 330 cut in the axial direction. The bobbin 330 is made of resin and has a cylindrical portion 331 and flange portions 332 and 333 at both ends of the cylindrical portion 331. On the inner periphery of the cylindrical portion 331 of the bobbin 330, recesses 331a and 331b in which the pole teeth 311 and 323 are accommodated are provided.

  In the assembled state as the B-phase stator 300, that is, in a state where the stator inner yoke 310 and the stator outer yoke 320 are coupled and the bobbin 330 around which the coil 340 is wound is housed inside the stator outer yoke 320. A part in the thickness direction of the pole teeth 311 is accommodated in the inner depression 331a, and a part in the thickness direction of the pole teeth 323 is accommodated in the depression 331b. A structure in which the pole teeth 311 and 323 are completely accommodated in the recesses 331a and 331b is also possible, but the thickness of the bobbin 330 needs to be increased accordingly.

  The front shape of the recess 331a viewed from the direction perpendicular to the axis has a shape matched to the pole tooth 311 and the shape of the recess 331b viewed from the same viewpoint has a shape matched to the pole tooth 332. . The pole teeth 311 and 323 are formed by press molding, and the recesses 331a and 331b are formed when the bobbin 330 made of resin is formed by an injection molding method. The stator outer yoke 320 and the stator inner yoke 310 having a plurality of pole teeth projecting at the center are arranged so as to sandwich the bobbin 330. It has a structure that fits. A clearance (gap) is provided between the outer peripheral surface of the pole teeth 311 and 323 and the inner peripheral surface of the bobbin 330 (the bottom surfaces of the recesses 331a and 331b: the surface on the axis center side). The side surface and the side surfaces of the depressions 331a and 331b are fitted with no clearance.

  A slight clearance is provided between the pole teeth 311 and 323 and the inner peripheral surface of the bobbin 330 because the pole teeth 311 and 323 are formed by pressing a sheet metal, so that the pole teeth 311 and 323 are bent. This is to absorb the above-mentioned tolerance and prevent the pole teeth 311 and 323 from entering the gap set between the rotor magnet 501 due to the tolerance when the bobbin 330 is molded. In other words, when the inner diameter of the bobbin 330 and the outer diameter of the pole teeth 311 and 323 viewed from the axial direction are designed without clearance, when the bobbin 330 is formed with a smaller inner diameter, the pole teeth 311 and 323 fall inward. There is a possibility that the gap between the pole teeth 311 and 323 and the rotor magnet 501 may be narrowed, and that the engagement between the pole teeth 311 and 323 may be shifted. In order to prevent this problem from occurring, the above-described clearance is provided so that the above-described deformation of the pole teeth 311 and 323 does not occur.

  The clearance provided between the outer peripheral surface of the pole teeth 311 and 323 and the inner peripheral surface of the bobbin 330 (the bottom surfaces of the recesses 331a and 331b: the surface on the axial center side) is filled with an adhesive. The pole teeth 311 and 323 are fixed to the bobbin 330. For example, an epoxy-based adhesive is used as the adhesive, but any type of adhesive can be used as long as it has a small sink after curing and has a certain degree of flexibility. An adhesive having a certain degree of flexibility and a Shore hardness of 50 or less is preferable.

  Further, in addition to the adhesion between the pole teeth 311 and 323 and the bobbin 330 described above, the flange portion 332 of the bobbin 330 and the stator inner yoke 310 are bonded, and the flange portion 333 of the bobbin 330 and the annular portion 322 of the stator outer yoke 320. Adhesion may be performed. This state is shown in FIG. FIG. 5 shows an example in which the pole teeth 311 and 323 and the bobbin 330 are bonded and the stator yoke and the flange portions 332 and 333 are not bonded.

  The above is the structure of the B-phase stator 300, but the A-phase stator 200 and the B-phase stator 300 have the same structure. A phase stator 200 and a B phase stator 300 are coupled back to back to form a stator 400. Here, convex portions and concave portions are provided on the opposing contact surfaces of the stator inner yoke 210 of the A-phase stator 200 and the stator inner yoke 310 of the B-phase stator 300, and the convex portions and the concave portions are fitted. Thus, the alignment of the A-phase stator 200 and the B-phase stator 300 is performed. Further, in the state in which the alignment is performed, the contact surfaces of the stator inner yoke 210 of the A-phase stator 200 and the stator inner yoke 310 of the B-phase stator 300 are fixed to each other by an adhesive. In the A-phase stator 200 and the B-phase stator 300, the outer peripheral portions of the stator outer yokes are fixed at a plurality of locations by welding.

  Inside the stator 400, the rotor 500 is housed in a rotatable state. The rotor 500 has a cylindrical rotor magnet 501. The rotor magnet 501 is a permanent magnet that is magnetized so that the polarity of SNSN.. The rotor magnet 501 is fixed to the outer periphery of a cylindrical rotor core 502. A shaft 503 serving as a rotation shaft is fixed to the center of the rotor core 502 via a sleeve 504.

  The shaft 503 is rotatably held on the front plate 600 by the bearing 601 and is rotatably held on the end plate 700 by the bearing 701. Front plate 600 is fixed to the annular portion of the stator outer yoke of A phase stator 200, and end plate 700 is fixed to the annular portion 322 of stator outer yoke 320 of B phase stator 300.

  Further, the position of the rotor core 502 in the axial direction is adjusted by a spacer 505, holders 506, and 507. The holders 506 and 507 have a bottomed cylindrical cup shape, are combined to face each other, and a coil spring 508 is accommodated inside thereof. A preload is applied to the bearings 601 and 701 by the coil spring 508.

(measurement data)
As a sample, the pole teeth 311 and 323 and the bobbin 330 are bonded, and the stator yoke and the flange portions 332 and 333 are not bonded. The sample of the first embodiment (structure of FIG. 5), the pole teeth 311 and 323 And the bobbin 330 are bonded together, and the stator yoke and the flange portions 332 and 333 are further bonded together. The sample of the second embodiment (the structure shown in FIG. 6), the bonding between the pole teeth 311 and 323 and the bobbin 330, A sample of a comparative example (the structure of FIG. 7) in which 330 and the stator yoke were not bonded was manufactured, and the other samples were manufactured in the same structure. And it driven on the same conditions and measured the noise in that case. The result of this measurement is shown in FIG. Table 1 below summarizes the differences between the samples.

  From FIG. 8, it can be seen that the noise reduction effect of 6.8 dB can be obtained by using the structure of the first embodiment as compared with the comparative example. Further, when the structure of the second embodiment is used, it can be seen that a noise reduction effect of 2.0 dB (8.8 dB with respect to the comparative example) can be obtained as compared with the structure of the first embodiment.

  In the experiment, compared with the state where the bobbin has grooves but the pole teeth are not bonded (Comparative Example), the noise level is greatly improved in the state where the pole teeth are further bonded (first embodiment). (See FIG. 8). This is because the pole teeth are fixed in the groove by forming a groove that can accommodate the pole teeth on the bobbin inner peripheral surface, but there is a slight clearance between the bobbin inner peripheral surface and the pole tooth outer peripheral surface, It is thought to cause vibration and cause noise. Therefore, the noise improvement effect is not enough just by attaching the groove for storing the pole teeth, and by fixing the outer peripheral surface of the pole teeth to the bobbin by adhesion, the pole teeth will not vibrate, and there is a great improvement effect on noise. It is assumed that it was obtained.

  In addition, when the back-to-back surfaces of the inner yokes in the comparative example are not bonded, the inner yoke 210 of the A-phase stator 200 and the inner yoke 310 of the B-phase stator 300 are simply pressed and brought into contact with each other. It has been found that noise increases further than the comparative example.

(Other)
The aspect of the present invention is not limited to the individual embodiments described above, and includes various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the contents described above. That is, various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 100 ... PM type stepping motor, 200 ... A phase stator, 210 ... Stator inner yoke, 300 ... B phase stator, 310 ... Stator inner yoke, 311 ... Polar teeth, 320 ... Outer stator yoke, 321 ... Cylinder, 322 ... Yen Ring part, 323 ... pole tooth, 330 ... bobbin, 331 ... cylindrical part, 331a ... hollow, 331b ... hollow, 332 ... flange part, 333 ... flange part, 340 ... coil, 400 ... stator, 500 ... rotor, 501 ... magnet , 502 ... Rotor core, 503 ... Shaft, 504 ... Sleeve, 505 ... Spacer, 506 ... Holder, 507 ... Holder, 508 ... Coil spring, 600 ... Front plate, 601 ... Bearing, 700 ... End plate, 701 ... Bearing.

Claims (4)

An inner yoke and an outer member each having a plurality of pole teeth positioned inside the bobbin are arranged so as to sandwich a bobbin having a substantially cylindrical portion in which an excitation coil is wound and a depression is formed on the inner periphery. Two sets of stators each including a yoke, wherein the plurality of pole teeth of the inner yoke and the plurality of pole teeth of the outer yoke are housed in the recess of the bobbin;
A rotor having a shaft, a rotor core fixed to the shaft, and a magnet disposed on an outer periphery of the rotor core, the rotor being rotatable with respect to the two sets of stators;
In the recess, the inner peripheral surface of the bobbin, the outer peripheral surface of the plurality of pole teeth of the inner yoke, and the outer peripheral surface of the plurality of pole teeth of the outer yoke are bonded by an adhesive. Type stepping motor.   A clearance is provided between the inner peripheral surface of the bobbin in the recess and the outer peripheral surface of the plurality of pole teeth of the inner yoke and the outer peripheral surface of the plurality of pole teeth of the outer yoke. The PM type stepping motor according to claim 1, wherein the adhesive is filled.   3. The PM type stepping motor according to claim 1, wherein both surfaces in the axial direction of the bobbin are fixed to each other on a surface where the inner yoke and the outer yoke are in contact with each other.   4. The PM type stepping motor according to claim 1, wherein opposing surfaces of the inner yokes of the two sets of stators are fixed by adhesion. 5.

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