JP5250211B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor.

  A clean room exists in a factory that handles precision equipment such as a semiconductor factory, and a fan filter unit (hereinafter referred to as FFU) is used in such a clean room. The FFU is provided with a filter on the downstream side of a fan driven by an electric motor, and supplies clean air into the clean room by filtering the air (see, for example, Patent Document 1).

  The FFU is often attached to the ceiling of a clean room, and from the viewpoint of effective use of space, downsizing is desired. Moreover, it may be attached to a single device, and in that case, a further thin structure is desired. Patent Document 1 shows an example in which the thickness is reduced by arranging an electric motor and a fan unit.

  Patent Document 2 discloses a three-phase claw pole type stepping motor. The motor of Patent Document 2 is thinned by arranging three-phase stator poles on the same plane.

  Patent Document 3 shows an example in which a three-phase claw-pole motor is configured by connecting stator cores corresponding to each phase in the axial direction and disposing the stator cores by 120 degrees each in the circumferential direction. It is disclosed. The stator core uses a powder magnetic core obtained by compression-molding magnetic powder, so that the shape of the claw magnetic pole that can improve the efficiency can be obtained.

JP 2000-205621 A JP 7-67312 A JP 2006-296188 JP

  In addition to the FFU disclosed in Patent Document 1, electric motors are used in many applications including refrigeration and air conditioning equipment and blowers. These motors are required to be highly efficient and thin, and are particularly noticeable with FFU as described above. In Patent Document 1, the thickness is reduced by the arrangement of the electric motor attached to the fan unit. However, the electric motor protrudes downward from the fan unit, and the thickness dimension of the FFU increases accordingly.

  In the FFU as shown in Patent Document 1, the vertical dimension is, for example, about 120 mm, and among these, the dimension of the electric motor occupies about 50 mm. Therefore, to further reduce the size of the FFU, it is required to reduce the size of the electric motor.

  In order to reduce the thickness of the electric motor, it is conceivable to reduce the size of the coil end portion that does not contribute to torque, or to eliminate the coil end portion itself.

  Patent Document 2 is premised on a stepping motor that does not require high torque. Therefore, it is possible to reduce the influence between the phases by increasing the distance between the phases arranged on the same plane, but it is difficult to realize high torque.

  Patent Document 3 improves the degree of freedom of the shape that can be formed by using a dust core and increases the efficiency of the motor, but has not been considered for a specific method of fixing the stator. That is, the powder magnetic core formed by compressing the magnetic powder is combined by pressing and compacting between the minute magnetic powders. Even if the shape formed by the binder or the like is maintained, for example, if a screw hole penetrating the core is provided in order to fix the core, stress concentrates around the screw hole.

  Since the dust core is only a magnetic powder that is pressed and bonded, there is a problem that chipping or cracking occurs around the screw hole, and local damage is likely to occur. At this time, performance deterioration and reliability reduction of the electric motor itself might be caused, and it was necessary to solve this.

  In addition, due to the reduction in thickness, the potential difference generated between the rotor and the stator inside the motor tends to cause electric corrosion on the ball rolling surface of the bearing, and the life of the bearing may be significantly shortened. If the bearing is damaged, the normal operation of the motor cannot be continued and the reliability of the motor itself has been reduced.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to improve performance and reliability while reducing the thickness of an electric motor using a core using a dust core.

A specific aspect of the present invention for achieving the above-described object is, for example, a stator core having a compact formed by compressing magnetic powder and a plane centered on the rotation axis of an electric motor between the compact and the compact. A stator having a plurality of coils disposed thereon, a rotor having a magnet on the outer peripheral side of the stator rotating around the rotation shaft, a base member to which the stator is fixed, the base member and the stator; an opening provided to said rotary shaft is penetrated, and a sleeve for positioning said stator core at said base member on by the inner walls of these openings is fastened to covering Utotomoni said base member, said stator core a nut member is inserted into the opening of the stator mounted on the opposite side of the base member across the, Yo is fixed to the rotating shaft extending to the outer peripheral side of said stator A click and, the,
The nut member has an opening through which the rotating shaft passes and a flange having a larger outer diameter than the opening of the stator, and the flange is located in a space between the stator and the yoke. ,
The molded body includes a plurality of extending portions extending in the radial direction and a claw portion extending in the axial direction from the extending portion, and the stator core is configured such that the molded body is overlapped with each other in the extending direction of the claw portion. And
A positioning pin that is fixed to the base member and restricts the rotation of the stator core is provided in a gap between the extending portions of the molded body positioned on the base member side .

Moreover, in the specific embodiment described above, more preferable embodiments are as follows.
( 1 ) The magnet and the yoke are formed by two-color molding.
( 2 ) Forming the magnet, the yoke, and the rotating shaft by two-color molding.
( 3 ) An insulating material is used for the sleeve to insulate between the bearing that holds the rotating shaft and the stator core.

  According to the present invention, it is possible to improve performance and reliability while reducing the thickness of an electric motor by using a core using a dust core.

  As an embodiment of the present invention, a configuration in which a molded body in which magnetic powder is compressed is arranged opposite to a stator core and the molded body made of the powder magnetic core is fixed without opening a hole will be described. . Specifically, in the following embodiment, a configuration is adopted in which the circumferential direction of the core is positioned with a pin and the axial direction is fixed with a nut. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing the FFU of this embodiment. A fan 2 is attached to the shaft of the electric motor 1 and is housed in a housing 3 together with a filter 4 to constitute a fan filter unit (FFU). The housing 3 has an opening on the upper side, and air is taken in from the opening as the fan 2 rotates. That is, air is sucked from the upper part in the drawing by the rotation of the fan 2 and passes through the filter 4 attached below the fan 2. When passing through the filter 4, the air is filtered and discharged to the downstream side (lower part in the figure) of the filter 4 as clean air.

  The FFU of this embodiment is attached to, for example, a ceiling portion of a clean room, and keeps supplying clean air to the clean room during operation of the FFU to keep the clean room clean.

  FIG. 2 is an exploded view of the electric motor of the present embodiment, and FIG. 3 is a cross-sectional view of the electric motor of the present embodiment. These show the electric motor 1 housed in the housing 3. The electric motor 1 of the present embodiment is a so-called outer rotor type electric motor, and the rotor includes a magnet 12, a yoke 11, and a shaft 10. The shaft 10 serves as a rotation axis of the electric motor 1, and the yoke 11 extending in the radial direction of the shaft 10 and the magnet 12 positioned on the outer peripheral side of the stator described later rotate around the shaft 10. When used for the FFU, the fan 2 is attached to the rotor, and the fan 2 is rotated by the rotation of the electric motor 1 to supply air into the clean room.

  On the other hand, the stator is provided with a coil 16 that is disposed so that a molded body (stator core 15) formed by compressing magnetic powder is opposed to each other and is sandwiched between the opposed stator cores 15. . Since the stator of this embodiment uses a dust core formed by compressing magnetic powder as the stator core 15, if a screw hole that penetrates the stator core 15 is provided, stress is generated around the screw hole. Concentration and local damage are likely to occur. Therefore, when fixing the stator, the following fixing method is adopted to suppress local damage.

  A sleeve 18 is fixed to the motor base 19 to which the stator is fixed by screws 20. The sleeve 18 has a tubular shape or a cylindrical shape, and the shaft 10 is inserted therein. Further, since the shaft 10 is inserted into the stator core 15, the central portion is opened, and the inner wall of the opening is covered with a sleeve 18.

  The position of the stator core 15 (the vertical position in FIG. 2 or the position in the front-rear direction of the paper surface) on the plane crossing the rotation axis is determined by the sleeve 18. That is, since the motor base 19 and the sleeve 18 are fastened by the screw 20, the stator core 15 is positioned on the motor base 19 via the sleeve 18.

  The position of the stator core 15 in the rotation axis direction is determined using the nut 14. The nut 14 of the present embodiment has a rotating shaft portion opened and a thread groove cut in the inner peripheral portion. A thread groove is also cut in the outer peripheral portion of the sleeve 18 on the side opposite to the motor base 19, and the nut 14 is fastened to the sleeve 18. Further, the nut 14 is provided with a flange portion having an outer diameter larger than the opening diameter of the stator core 15. The stator core 15 is positioned in the rotational axis direction by the outer peripheral surface of the nut 14 and the flange portion of the nut 14. In this embodiment, the stator core 15 is positioned by contacting the nut 14 and the stator core 15. The nut 14 is mainly made of a nonmagnetic metal.

  A pin 17 is used for positioning the stator core 15 in the rotational direction. The pin 17 is mainly made of a nonmagnetic metal and is disposed so as to be fitted with a constricted portion of the stator core 15. Specifically, description will be made with reference to FIG. 4 in addition to FIGS.

  4 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 4, the stator core 15 of the present embodiment has an opening at the center, and is provided with a plurality of extending portions extending in the radial direction. Further, a claw portion that extends in the direction of the pair of stator cores is provided at the tip of the extending portion. That is, in FIG. 4, the claw portions extend in the front direction of the paper surface. In other words, the stator core 15 is configured by overlapping each other in the extending direction of the claw portions.

  In FIG. 4, the stator core 15 is provided with six extending portions at equal intervals, and pins 17 are arranged in the gap portions of the extending portions. Specifically, a concave constricted portion is formed between the root portions of the extending portion, and the pins 17 are arranged so as to be accommodated in the constricted portion. In the example shown in FIG. 4, the pins 17 are arranged at three positions at equal intervals in the circumferential direction to restrict the stator core 15 from rotating about the axis.

  In the present embodiment, a three-phase coil is arranged on a plane centering on a shaft 10 that serves as a rotation axis of the electric motor 1. Specifically, a columnar portion convex in the axial direction is provided at the base portion of the six extending portions, and a coil is wound around the columnar portion. Assembly is improved by attaching the pin 17 to the constricted portion located between the coils, and the stator core 15 can be fixed.

  5 is a cross-sectional view taken along line BB in FIG. Six pairs of claw portions of the stator core 15 are arranged on the outer peripheral portion of the stator composed of the stator core 15 and the coil 16, and the rotor magnet 12 is positioned on the outer side thereof. The axial direction of the stator is fixed by a nut 14, a sleeve 18, a motor base 19, and a screw 20, and the rotor is supported by a bearing 13 assembled to the sleeve 18.

  Accordingly, by causing a current to flow through the coil 16 and generating a rotating magnetic field, a force in the rotating direction is generated in the magnet 12 and the rotor rotates. The axial direction of the rotor is fixed by a retaining ring 22 (see FIG. 2). Furthermore, a preload is applied to the bearing 13 by a spring 21 to improve rotation accuracy and prevent vibration (see FIG. 2).

  Next, the configuration of the rotor and the stator will be described in more detail. A magnet 12 used in the rotor is bonded to a yoke 11 made of a magnetic material and integrated with the yoke 11. The yoke 11 may be made of a magnetic powder material. In this case, the yoke 11 and the magnet 12 may be integrally formed by two-color molding. The shaft 10 and the yoke 11 are fastened by various methods such as adhesion, press-fitting, shrink fitting, and welding. When the yoke 11 is made of a magnetic powder material, the shaft 10 and the yoke 11 are integrated. You may shape | mold.

  With regard to the configuration of the stator, the stator core 15 is a dust core obtained by compression-molding iron powder subjected to insulation treatment. And the iron core part of a coil and the nail | claw-shaped part used as a magnetic pole are formed in the circumference at equal intervals. Moreover, in order to eliminate the magnetic interference of adjacent, it has the shape which was greatly narrowed toward the center side from the virtual circle used as an outer periphery. As a result, a plurality of extending portions are provided from the central portion toward the outer diameter direction, and a tip portion of the extending portion, that is, a claw portion positioned on the outer circumference serves as a magnetic pole.

  The coil 16 is formed by winding an electric wire, but may be wound around a bobbin made of an insulating material. The coil 16 is configured to be sandwiched between two stator cores 15, and the stator core 15 and the coil 16 are integrally molded using resin.

  The sleeve 18 for fixing the stator and the shaft 10 may be integrated with the motor base 19, but may be a separate part as shown in FIG. When separate parts are used, the sleeve 18 is preferably made of an insulating material such as resin. This is to suppress electrolytic corrosion of the bearing 13 caused by a potential difference between the stator core 15 constituting the stator and the shaft 10 constituting the rotor.

  In the present embodiment, as shown in FIG. 3, the inner wall of the opening of the stator core 15 is covered with a sleeve 18, and a shaft 10 serving as a rotating shaft by a bearing 13 is placed inside the tubular or cylindrical sleeve 18. Has been inserted. Therefore, even if a potential difference is generated between the rotor and the stator, by using an insulator for the sleeve 18, conduction through the bearing 13 does not occur, and electrolytic corrosion of the bearing 13 can be suppressed. Therefore, an inexpensive steel bearing can be used without using a ceramic bearing, and the cost can be reduced.

  In addition, a space (gap) is provided between the stator core 15 and the yoke 11, and insulation between the rotor and the stator is achieved by the sleeve 18 and the gap. In addition, by adopting a structure in which the flange portion of the nut 14 is arranged in the gap, the electric motor 1 can be thinned and can be used for various applications such as FFU that require thinning. Yes.

  According to the embodiment described above, it is possible to improve performance and reliability while using a core using a dust magnetic needle in order to realize a thin motor.

The figure which shows FFU of a present Example. The exploded view of the electric motor of a present Example. Sectional drawing of the electric motor of a present Example (CC sectional drawing of FIG. 5). AA sectional drawing of FIG. BB sectional drawing of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Fan, 3 ... Housing, 4 ... Filter, 10 ... Shaft, 11 ... York, 12 ... Magnet, 13 ... Bearing, 14 ... Nut, 15 ... Stator core, 16 ... Coil, 17 ... Pin , 18 ... sleeve, 19 ... motor base, 20 ... screw, 21 ... spring, 22 ... retaining ring.

Claims (4)

A stator having a stator core having a compact formed by compressing magnetic powder and the stator having a plurality of coils disposed on a plane centering on a rotation axis of an electric motor between the compact and the rotation axis; A rotor that rotates around the center and has a magnet on the outer peripheral side of the stator, a base member to which the stator is fixed, an opening provided in the base member and the stator and through which the rotating shaft passes, and a sleeve for positioning said stator core at said base member on by being fastened to Utotomoni the base member covering the inner wall, the opening of the stator mounted on the opposite side of the base member across the stator core A nut member inserted into the yoke, and a yoke that is fixed to the rotating shaft and extends toward the outer peripheral side of the stator,
The nut member has an opening through which the rotating shaft passes and a flange having a larger outer diameter than the opening of the stator, and the flange is located in a space between the stator and the yoke. ,
The molded body includes a plurality of extending portions extending in the radial direction and a claw portion extending in the axial direction from the extending portion, and the stator core is configured such that the molded body is overlapped with each other in the extending direction of the claw portion. And
An electric motor comprising a positioning pin that is fixed to the base member and regulates rotation of the stator core in a gap between the extending portions of the molded body positioned on the base member side .   The electric motor according to claim 1, wherein the magnet and the yoke are formed by two-color molding.   The electric motor according to claim 1, wherein the magnet, the yoke, and the rotating shaft are formed by two-color molding.   The electric motor according to claim 1, wherein an insulating material is used for the sleeve to insulate between a bearing for holding the rotating shaft and the stator core.

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