JP2006087190A - Motor having noncylindrical gap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the axial vibration of a motor shaft, with the change of the structure of a rotor. <P>SOLUTION: This is a motor which is equipped with a stator, where winding is applied, a magnet, winding, and a cage type conductor. As for the form of a gap section where the stator and the rotor face each other, the gap is constituted of not cylinders having the same radii but spherical surfaces, or in combination of cylinders having two or more radii or in combination of a cylinder and a cone. This reduces the vibration generated in its axial direction, and reduces the vibration and noise of the motor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor having a non-cylindrical gap suitable for a drive motor for industrial use, home electric appliances, OA equipment, a fan motor, etc. with reduced vibration and noise.

  Usually, a fan motor is used for cooling the device and blowing air. While these motors are required to have high efficiency, there is a demand for reducing vibration and noise. In order to reduce the vibration and noise of these motors, a molded motor is employed for the purpose of increasing the mechanical rigidity of the motor and reducing the transmission of electromagnetic vibration generated by the motor. In Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-231192) and Patent Document 2 (Japanese Patent Application Laid-Open No. 6-78486), by molding the entire stator core portion including the windings of the motor, between laminated cores and the like Is filled with resin to reduce transmission of electromagnetic vibration generated from the stator core.

  As other methods for reducing vibration and noise, Patent Document 3 (Japanese Patent Laid-Open No. 8-70550), Patent Document 4 (Japanese Patent Laid-Open No. 6-30549), and Patent Document 5 (Japanese Patent Laid-Open No. 8-298740). As shown in Fig. 4), the accuracy of each part such as the assembly accuracy of the stator and bearing, the assembly accuracy of the shaft and rotor, and the assembly accuracy are improved. It is described that the generation is suppressed and the vibration and noise of the entire motor are reduced.

JP 2001-231192 A JP-A-6-78486 JP-A-8-70550 JP-A-6-30549 JP-A-8-298740

  The present invention focuses on the fact that noise of a fan motor or the like is related to the axial vibration of the motor, and is to reduce the axial vibration generated by the motor itself that is the excitation source of the axial vibration. The fan motor normally rotates at a high speed, and has a function of generating wind by rotation of a fan (blade) attached to the shaft of the motor rotor. The blade receives a reaction force due to the generation of wind, and receives a thrust in a direction opposite to the direction in which the wind flows. Due to the thrust, the rotor loses the balance maintained at the magnetic center with the stator, and exerts a force in the direction opposite to the thrust of the blade by the magnetic attraction between the rotor and the stator.

  This magnetic attraction force varies depending on the rotor rotation position depending on the stator slot and the number of rotor poles. During rotation, the number corresponding to the least common multiple of the number of poles and the number of slots in one rotation is similar to the cogging torque of the motor. Will be repeated. The vibration in the axial direction is generated by the relationship between the thrust of the blade and the magnetic attractive force.

  Since this vibration does not occur when there is no deviation between the stator and the rotor, a structure in which the position of the rotor in the thrust direction is fixed can be considered. However, since mechanical friction increases, mechanical loss increases and motor efficiency decreases. In the present invention, axial vibration is suppressed by changing the structure of the rotor.

  In the present invention, since the rotor does not deviate from the magnetic center of the stator and the rotor by the thrust of the blades, the cylindrical gap surface of the conventional stator and the rotor is used as a structure that balances the magnetic attraction force at the gap portion. Therefore, a structure is also proposed in which the axial repulsive force is also utilized, and the axial vibration can be reduced by balancing with the gap structure.

  Even if thrust of the fan (blade) is generated as described above, by covering the magnetic attraction force facing it with the gap surface, vibration in the axial direction can be reduced, and the noise of the motor can be reduced. Further, the axial thrust can be reduced even with respect to magnetic center deviation due to assembly error, magnet magnetization error, and the like.

  Even if the fan (blade) thrust is generated as described above, the axial magnetic repulsive force facing it can be covered with the gap surface to reduce the axial vibration and reduce the motor noise. It becomes possible. Further, the axial thrust can be reduced even with respect to a magnetic center shift due to an assembly error, a magnetizing error, or the like.

(Embodiment 1)
An embodiment of a motor according to the present invention will be described with reference to the drawings.

  FIG. 1 is a simplified cross-sectional view showing a basic motor structure (cross section) which is an embodiment of a motor according to the present invention. In general, since a motor is configured using a laminated steel plate (silicon steel plate or the like) as a stator core, the gap between the rotor and the stator has a cylindrical shape with a constant radius from the rotor center.

  The rotor rotates by generating torque in the rotation direction by the rotating magnetic field generated by the stator coil. However, since the motor is free in the axial direction, in a motor that receives thrust, such as a fan motor, or in a motor that has produced an assembly error in the axial direction or a magnetization distribution error in the magnet, Vibration occurs. In order to reduce the occurrence of this axial vibration, in the present invention, the structure shown in FIG. 1 is used, and the attractive repulsion due to the magnetic field is balanced in the axial direction.

  In the embodiment shown in FIG. 1, the axial cross section of the rotor magnet 12 constituting the rotor 10 is non-linear, for example, circular or elliptical, and the stator core 14 side is also the same as the shape of the rotor 10. The shape is the opposite shape. That is, the gap portion G formed on the opposing surface of the rotor magnet 12 supported by the shaft 16 and the stator core 14 surrounding the outer periphery thereof is non-cylindrical, for example, spherical, conical, and cylindrical. By adopting the combination shape, the vibration in the axial direction can be reduced.

  A gap G formed between the outer peripheral surface of the rotor magnet 12 and the inner peripheral surface of the stator core 14 has an axial component and a component perpendicular to the axial direction. On the other hand, the structure of the conventional motor is a cylindrical rotor magnet, and there is no axial component, and all components are perpendicular to the axial direction. A stator coil 18 is disposed on the stator core 14.

  In the shape shown in FIG. 1, the rotor 10 and the stator core 14 have a gap center portion that does not include the axial component, and upper and lower end portions that include the axial component. A rotating torque is generated by the magnetic field, and the rotor 10 rotates. In addition, at the upper and lower ends, the same suction or repulsion force is generated vertically. This suction / repulsion force is the same at the top and bottom of the same section during rotation. As a result, the axial position of the rotor is positioned at a balanced position, so that the magnetic center can be maintained and axial vibration can be reduced even when an external thrust or the like is applied.

  Next, an example of the motor assembly method of this embodiment will be described with reference to FIG. First, as shown in FIG. 2A, the stator core 14 is formed by molding a magnetic powder material such as a dust core and a sintered core for one pole of the stator core 14 of the motor using a molding die. This material is suitable for forming a three-dimensional shape as compared with a laminated structure of silicon steel plates or the like. At this time, the shape has a shape matched to the shape of the rotor facing the tooth tip 20 that becomes the gap portion. In addition, a body shape that allows the stator coil 18 to be easily wound can be manufactured by molding at the same time.

  Next, the stator coil 18 is aligned and wound as shown in FIG. 2 (b), and the rotor 10 is arranged as shown in FIG. 2 (c), and the stator core 14 is arranged and assembled from the circumferential direction. Then, the stator core 14 is fixed by a method such as welding, bonding, housing press-fitting, shrink fitting, etc., and assembly is performed. As a result, a motor having a cross section as shown in FIG. 1 can be obtained. Further, by setting the R surface of the rotor magnet 12 to one side in the axial direction, the stator core 14 can be assembled first without being arranged around the rotor 10, and then the rotor can be moved from the side without the R. It is also possible to assemble in the axial direction.

  By using a motor having a non-cylindrical gap assembled in this way as a fan motor as shown in FIG. 8, a motor with less axial vibration and less noise can be configured. In FIG. 8, the rotor magnet 10 is rotatably supported by the shaft 16. The shaft 16 is supported by a bearing 28 supported by the lower motor case 26a and a bearing 30 supported by the upper motor case 26b.

The stator core 14 is accommodated in the upper and lower motor cases 26b and 26a. The stator coil 18 is wound in a groove formed in the stator core 14. A leaf spring 32 is inserted between the upper end of the bearing 30 and the upper motor case 26b to press the rotor 10 downward. Fan blades 34 are fixed to the shaft 16 by nuts 36. A motor control board 38 is fixed on the stator core 14.
(Embodiment 2)
FIG. 3 is a schematic sectional view showing the second embodiment. In the first embodiment shown in FIG. 1, the cross-sectional shape is circular, but FIG. 3A shows a motor in which the upper and lower parts are substantially conical and the central part is cylindrical. FIG. 3B shows a conical shape in which the upper and lower parts are opposite to each other and a cylindrical part in the central part. This shape can also be assembled by the assembling method shown in the first embodiment, and axial vibration can be reduced.
(Embodiment 3)
FIG. 4 is a schematic sectional view showing the third embodiment. The structure of the stator core 14 and the rotor 10 has the same structure as that of the first embodiment shown in FIG. 1, and the relationship between the shaft 16 and the stator is as shown in the figure. That is, a part of the stator core 14 has a shape that becomes a holding portion of the bearing 22. Since a powder material such as a powder magnetic core can be molded in a three-dimensional shape with a mold, a shape for holding the bearing 22 in the axial direction can be formed at the time of molding.

By arranging the bearing 22 in this portion, there is a problem that the bearing position with respect to the stator varies due to manufacturing errors (overlapping of dimensional tolerances) of the housing 40, the bracket 42, etc. Can be solved. As a result, the axial position of the rotor 10 can be kept unique, so that the axial rotor position can be made constant in addition to the axial vibration reduction described in the first embodiment.
(Embodiment 4)
FIG. 5 shows a fourth embodiment of the present invention. The structure of the stator core 14 and the rotor 10 is the same as that of the first embodiment shown in FIG. 1, and a lubricating resin or an oil-impregnated metal is applied to the gap surface of the rotor 10 or the stator core 14. The gap portion of the magnetic circuit is also used as a mechanical bearing 44 in the rotational direction and the thrust direction. Thereby, the rotor is uniquely positioned in the axial direction, and in addition to the reduction of the axial vibration shown in the first embodiment, it is possible to make the rotor position in the axial direction constant.
(Embodiment 5)
6 and 7 show a fifth embodiment of the present invention. The gap between the stator cores 14a, 14b and the rotor 10 has the same structure as that of the embodiment shown in FIG. 1, and the stator side core is divided at the center. In this embodiment, the axial lengths of the stator coils 18 of the stator cores 14a and 14b are shorter than the axial lengths of the gap portion and the core back portion, and the rotational direction positions are shifted and combined in two or more stages. This constitutes the stator. Further, the stators 14a and 14b divided in the axial direction are assembled by shifting a certain angle in the rotation direction, and the same current is supplied to the slots in the windings.

  In general, in a small motor, the motor is often driven by a method in which a current of a 120-degree rectangular wave is applied. In such motors, torque pulsations and thrust vibrations of the least common multiple of the number of slots of the stator and the number of rotor poles are generated in the rotational torque and axial thrust, which are often problematic.

  In a motor having a non-cylindrical gap as in the present invention, it is possible to suppress the occurrence thereof, but some minute vibration may remain in some cases. Therefore, a structure in which the minute vibrations are overlapped to be zero is shown. Normally, vibration of the least common multiple is generated in one rotation. Therefore, the vibration is made zero by dividing the stators 14a and 14b into upper and lower parts and rotating them in consideration of the period.

  FIG. 7 shows an example of vibration of a 12-slot 8-pole motor. In this slot combination, 24 vibrations of the least common multiple are generated per rotation. Accordingly, since one cycle of vibration is generated at a rotation angle of 15 degrees, the upper and lower stators 14a and 14b are assembled by shifting the upper and lower stators 14a and 14b by 7.5 degrees to synthesize vibration waves generated at the upper and lower positions, and the vibration becomes zero. .

It is explanatory drawing which showed the cross section of the motor rotor and stator which show the 1st Embodiment of this invention. It is explanatory drawing which showed an example of the assembly method of the motor rotor of FIG. 1, and a stator. It is explanatory drawing which showed the cross section of the motor rotor and stator which show the 2nd Embodiment of this invention. It is the figure which showed the cross section of the motor rotor which shows the 3rd Embodiment of this invention, and a stator, and is drawing explaining the relationship of arrangement | positioning of a stator and a bearing. It is the figure which showed the cross section of the motor rotor and stator which shows the 4th Embodiment of this invention, and is drawing explaining the structure of a stator, a rotor, and a bearing part. It is the figure which showed the cross section of the motor rotor and stator which shows the 5th Embodiment of this invention, and is drawing explaining the structure of a some stator and rotor, and a bearing part. It is the figure which showed the vibration waveform which generate | occur | produces in the axial direction of the motor of this invention, and a rotation direction. It is sectional drawing which showed the example which applied the motor of this invention to the fan motor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Rotor, 12 ... Rotor magnet, 14 ... Stator core, 16 ... Shaft, 18 ... Stator coil, 22 ... Bearing, 26a, 26b ... Motor case, 32 ... Leaf spring, 30 ... Ball bearing, 34 ... Fan blade, 36 ... nut, 38 ... motor control board, 40 ... housing, 42 ... end bracket.

Claims (5)

  A stator having a winding and a rotor having a magnet, and the shape of the gap portion where the stator and the rotor face each other is a spherical surface, or a combination of cylinders having a plurality of radii, or a cylinder and a cone A motor having a non-cylindrical gap, which is constituted by a combination.   A stator provided with a winding, and a rotor having a magnet, and the shape of a gap portion where the stator and the rotor face each other is spherical, or a combination of cylinders having two or more radii, or a cylinder A motor having a non-cylindrical gap, characterized by comprising a conical combination and having a structure in which a part of the stator core is used for fixed positioning of a bearing.   A stator having windings, and a rotor having a magnet, and the shape of a gap portion facing the stator and the rotor is a spherical surface, or a combination of cylinders having two or more radii, or a cylinder A non-cylindrical shape characterized by comprising a combination of cones, a lubricating resin or oil-impregnated metal disposed on the gap surface, and the gap portion of the magnetic circuit being configured as a mechanical bearing in the rotational direction and thrust direction A motor with a gap.   A stator having windings, and a rotor having a magnet, and the shape of a gap portion facing the stator and the rotor is a spherical surface, or a combination of cylinders having two or more radii, or a cylinder Composed of a conical combination, the axial length of the winding portion of the stator is made shorter than the axial length of the gap portion and the core back portion, and the rotational direction position is shifted and combined in two or more stages. A motor having a non-cylindrical gap characterized by comprising a stator to superimpose torque pulsation, axial vibration in the thrust direction, etc., and simultaneously suppressing vibration in both directions. A stator having windings and a rotor having a magnet and inserted into the inner periphery of the stator, and the shape of the gap portion where the stator and the rotor face each other is spherical, or a plurality of A motor having a non-cylindrical gap, characterized by a combination of a cylinder having a radius, or a combination of a cylinder and a cone, the opposing gaps including an axial component and a radial component.

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