JP2005318672A - Magnet motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnet motor which prevents a neodymium ring magnet from cracking is reduced in vibration caused by the unbalance of a rotor, small in torque ripple, high in performance and high in reliability. <P>SOLUTION: A ring-like elastic element 3 is interposed in a gap between the ring magnet 1 and a rotary shaft 2 of a yoke, and fixed with an adhesive to constitute an inner rotor. As the ring-like elastic element 3, a specially manufactured O ring, a rubber band, etc. may be used. A groove is formed on the rotary shaft 2 by considering the gap and the sectional shape of the elastic element 3. The ring magnet is in a relatively contraction direction due to the difference of thermal expansion coefficients, and a gap between the ring magnet 1 and the rotary shaft 2 becomes small. However, an initial gap is averaged by providing the elastic element 3. Stress applied to the ring magnet 1 is dispersed to suppress the crack of the magnet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel fixing configuration of a rotor of a magnet motor using a neodymium ring magnet used for industrial equipment, home appliances, and the like.

  Conventionally, industrial motors are required to have a small size and high output, and powerful segment magnets such as neodymium sintered magnets are used for rotors. In the case of a magnet rotation type inner rotor motor, a magnet is generally mounted on the circumference of a rotating shaft of a magnetic material supported by a bearing as a rotor.

  The rotor of this magnet motor employs a construction method in which segment magnets are arranged at equal intervals on the outer periphery of the rotating shaft and fixed with an adhesive, and a magnetic path is formed by the segment magnet, the rotating shaft and the stator. .

On the other hand, there are many cases in which a ring-shaped neodymium sintered magnet is used. In this case, the magnet adhesion surface of the rotating shaft is usually matched to the shape of the inner diameter of the ring magnet (see, for example, Patent Document 1).
JP 2003-274588 A

  The problem to be solved is that the rotor of the magnet motor leads to cracking of the ring magnet due to thermal contraction and thermal expansion due to a change in ambient temperature.

  In the adhesion between the segment magnet and the rotating shaft, scattering due to peeling of the segment magnet was a problem, but in the adhesion between the neodymium sintered ring magnet and the iron-based rotating shaft, the ring at a high temperature due to the difference in thermal expansion coefficient. The gap between the magnet and the rotating shaft was narrowed, and in the worst case, the ring magnet could be broken and scattered.

  In particular, in the case of neodymium sintered magnets, the coefficient of thermal expansion becomes negative, so the stress generated at high temperatures increases. If the gap between the ring magnet and the rotating shaft is non-uniform, the stress in the narrow gap will concentrate and accelerate the cracking of the ring magnet.

  On the other hand, when the initial gap setting is increased, the ring magnet is easily eccentric with respect to the rotating shaft, and the unbalance amount increases and vibration is generated. Similarly, there has been a problem that cogging torque and torque ripple become large due to eccentricity.

  The present invention solves the above-mentioned problems, and provides a high-performance and highly reliable magnet motor that prevents cracking of a neodymium ring magnet, reduces vibration due to rotor unbalance, and has low torque ripple. With the goal.

  In order to solve the above-mentioned problems, the present invention provides a motor having a rotor having a neodymium sintered ring magnet mounted on the outer peripheral surface of a yoke, and is bonded and fixed with an elastic body interposed between the yoke and the ring magnet. This is a magnet motor having an inner rotor, and since the adhesive layer can be made uniform by interposing an elastic body in the gap between the ring magnet and the yoke, cracking of the ring magnet due to stress concentration can be prevented.

  According to the magnet motor of the present invention, since the gap between the yoke and the ring magnet can be made uniform, the ring magnet can be prevented from cracking due to stress concentration.

  Moreover, the amount of eccentricity of the ring magnet with respect to the yoke is reduced by the elastic body interposed in the gap. As a result, an unbalance amount is reduced and vibration is suppressed, and a high-performance and highly reliable magnet motor with small cogging torque and torque ripple is obtained.

  In FIG. 1, a ring-shaped elastic body 3 is interposed in a gap (about 0.1 mm) between a neodymium sintered ring magnet 1 (hereinafter referred to as a ring magnet) and a rotary shaft 2 that is a yoke, and an adhesive. The inner rotor is configured by fixing with The configuration other than the inner rotor is a general magnet motor, and the overall configuration diagram and description thereof are omitted.

  A special O-ring, rubber band or the like may be used for the ring-shaped elastic body 3, and a groove portion is provided on the rotating shaft 2 in consideration of a small gap and a cross-sectional shape of the elastic body 3. When the ring magnet 1 is mounted on the rotary shaft 2, the movement of the elastic body 3 in the axial direction is restricted by this groove.

  When the magnet motor becomes hot due to driving or the like, the ring magnet 1 and the rotary shaft 2 constituting the inner rotor also become hot. The ring magnet is relatively contracted in the contraction direction due to the difference in thermal expansion coefficient between them, and the gap between the ring magnet 1 and the rotating shaft 2 is reduced. However, the initial gap is made uniform by providing the elastic body 3, the stress applied to the ring magnet 1 is dispersed, and the cracking of the magnet is suppressed.

  Also, the fact that the gap is made uniform when the rotating shaft 2 and the ring magnet 1 are fixed is equivalent to the fact that the eccentric amount of the ring magnet 1 with respect to the rotating shaft 2 is suppressed, and the unbalance amount becomes small, and the motor rotation. Vibration at the time is suppressed. Similarly, since the gap between the stator and the stator is made uniform, the cogging torque and torque clip are suppressed in the stator having the iron core, and the magnet motor has a high rotational accuracy. Further, even a coreless type stator has a small eccentricity and therefore a magnet motor with a small torque ripple.

  In the conventional bonding method using only an adhesive, the gap between the ring magnet 1 and the rotary shaft 2 cannot be controlled, and the gap between the ring magnet 1 and the rotary shaft 2 becomes uneven. That is, when the rotating shaft 2 is held horizontally during the curing of the adhesive, the upper gap of the ring magnet 1 is reduced by gravity and the lower gap is increased. Even if the rotation axis 2 is kept vertical, the circumferential gap between the end faces of the ring magnet 1 becomes uneven due to the cylindricity of the end face and the inner diameter, and stress concentrates on the narrow part of the gap, causing magnet cracks. It was connected to.

  In Example 1, since the non-uniformity of the gap can be eliminated by interposing a ring-shaped elastic body in the gap between the ring magnet and the rotating shaft, the possibility that the ring magnet breaks due to the stress being dispersed is not possible. Reduce significantly.

  Even a rotor yoke in which a laminated iron core is press-fitted on the rotating shaft can be similarly implemented because the thermal expansion coefficients of the rotating shaft and the laminated iron core are close.

  In the second embodiment, the ring-shaped elastic body of the first embodiment is replaced with a tape-shaped elastic body. The neodymium sintered ring magnet is the same, and the elastic body will be mainly described.

  In FIG. 2, the tape-like elastic body 23 is made of felt, sponge, or the like, and is provided with an adhesive on one side to form a tape. Thereby, it can attach easily on the rotating shaft 22, and the movement of the elastic body 23 can be prevented.

  By disposing the elastic body 23 on the circumference in the vicinity of both ends where the ring magnet 21 on the rotating shaft 22 is disposed, the unevenness of the gap can be minimized. Further, an adhesive is applied between the elastic bodies 23 to fix the ring magnet 21. The elastic body 23 also serves to prevent the adhesive from leaking out. Further, depending on the thickness of the elastic body 23, a groove portion may be provided on the rotating shaft 22 to correspond to the gap.

  As described above, since the gap between the ring magnet and the rotating shaft after being secured is at least as much as the thickness of the tape-like elastic body 23, eccentricity is suppressed, so that cracking of the ring magnet due to stress concentration can be suppressed. At the same time, since the amount of eccentricity is also suppressed, the magnet motor is reduced in vibration and torque ripple.

  In Example 3, the elastic body is formed into a thread shape. In FIG. 3, the elastic body 33 is spirally wound on the circumference of the rotating shaft 32, and an adhesive is applied on the rotating shaft 31. After that, the magnet 31 is mounted on the elastic body 33.

  Since the thread-like elastic body 33 secures the gap between the ring magnet 31 and the rotary shaft 32 by the thickness of the thread of the elastic body 33, the possibility of the ring magnet 31 breaking is reduced. As in the above embodiment, vibration and torque ripple can be suppressed.

  The magnet motor of the present invention is most suitable for industrial-use servomotors that are used at high speeds in a high temperature environment.

Sectional drawing of the rotor in Example 1 of this invention Sectional drawing of the rotor in Example 2 of this invention Sectional drawing of the rotor in Example 3 of this invention

Explanation of symbols

1,21,31 Ring magnet 2,22,32 Rotating shaft (yoke)
3,23,33 Elastic body

Claims (3)

A motor having a rotor having a neodymium sintered ring magnet mounted on an outer peripheral surface of a yoke, and having an inner rotor bonded and fixed with an elastic body interposed between the yoke and the ring magnet. The magnet motor according to claim 1, wherein a tape-like elastic body is disposed in the vicinity of both ends to which the ring magnet on the yoke is fixed. 2. The magnet motor according to claim 1, wherein a thread-like elastic body is spirally arranged between the axial directions to which the ring magnet on the yoke is fixed.