JP2008278623A - Highly efficient and low-noise motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the improvement of efficiency by further increasing flux density and low vibration, which is a common target to motors, in a magnetically soft material having a dust core body formed by compression molding of magnetic powder, and to provide a highly efficient and low noise motor using such a magnetically soft material. <P>SOLUTION: In a magnetic core of a motor, magnetic steel sheet is arranged inside so as to be in parallel to magnetic flux flowing direction and a stator formed by covering the magnetic steel sheet with the magnetic powder and a lubricant is used. When the stator is of a three-dimensional structure, the magnetic steel sheet is arranged by bending so as to go along the magnetic flux flowing direction without cutting it. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor applied to, for example, driving of various electric vehicles, FA devices, electric bicycles, electric scooters, vacuum cleaners, and the like, and more particularly to a soft magnetic material and a motor using the same.

  In recent years, miniaturization of electric and electronic devices has progressed, and accordingly, higher power and higher efficiency are required. In particular, motors are used in various products as “industrial rice” alongside semiconductor products. For example, in the camera industry, in recent years, the automation of functions has progressed, and this small electric motor is used for an autofocus and zoom lens drive circuit, an automatic film winding mechanism, and the like.

  Among small motors, a claw pole type synchronous motor including a PM type two-phase stepping motor has a structure that can be manufactured at low cost, and a typical one is described in Non-Patent Document 1.

  Conventional claw-pole type synchronous motors were originally used in the low frequency range for stepping operation, but in recent years, they have been used in equipment operating in the low speed to high speed areas such as OA equipment. Therefore, what operates in a low frequency range to a high frequency range is needed.

  However, in the conventional claw-pole type synchronous motor, the claw pole, that is, the pole teeth, has an increased area in order to place importance on the torque, and therefore can only operate in a low frequency range. On the other hand, it is possible to operate in the high frequency range by simply reducing the area of the pole teeth, but in this case, a large torque cannot be obtained. In any case, the conventional claw pole type synchronous motor has a problem that the operating range from the low frequency range to the high frequency range cannot be covered without reducing the torque so much.

  Further, in the conventional axial motor using a dust core, the magnetic flux density parallel to the pressurizing direction at the time of molding is inferior to that in the perpendicular direction, so that the magnetic permeability is lower than that of a motor using an iron core. In particular, this tendency is prominent in magnetic cores having thin bosses and skirts. Furthermore, in the stator core of a solenoid valve having boss and skirt parts, the pressurizing direction of these parts becomes a magnetic path, so improvement of the magnetic flux density in that direction becomes a problem in increasing the opening and closing force of the valve. ing.

Takashi Kenjo, “Stepping Motors and their microprocessor controls”, p. 40-P. 43, Oxford University Press, 1986 reprint

  Therefore, the present invention aims at improving efficiency by further increasing the magnetic flux density and reducing vibration, which is a common goal for motors, in a soft magnetic material having a dust core body formed by compression molding magnetic powder. It is a problem to provide a motor with high efficiency and low noise using a soft magnetic material.

Specific means of the present invention for solving the above-described problems are as follows.
(1) A motor using a magnetic core formed by arranging an electromagnetic steel plate along a direction in which magnetic flux flows and enclosing the electromagnetic steel plate with magnetic powder and a lubricant.
(2) In the magnetic core, the stator structure is a three-dimensional structure, the electromagnetic steel sheet is arranged along the flow direction of magnetic flux without being cut in the middle, and the electromagnetic steel sheet is wrapped with magnetic powder and a lubricant. The motor according to (1), wherein a stator is formed using a magnetic core.
(3) (1) or (2), wherein in the magnetic core, the gap between the rotor and the teeth of the electromagnetic steel sheet disposed at the tip of the teeth is sequentially increased with respect to the rotation direction of the rotor. Motor.

  According to the present invention, the magnetic steel sheet is embedded in the magnetic powder so as to be parallel to the magnetic flux flow direction, the magnetic steel sheet is bent in the magnetic flux flow direction, and the electromagnetic steel sheet disposed at the tip of the teeth is rotated with respect to the rotation direction. By using a magnetic core that increases the gap with the rotor, a high-efficiency, low-noise motor can be obtained.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing an axial motor using a permanent magnet according to one example. The motor includes a rotor 1 and a stator 2, and the stator 2 includes a core, an upper winding, and a lower winding. The core includes a first upper magnetic core 3 and a second lower magnetic core 4. The upper magnetic core 3 can be grasped as a layer laminated with respect to the lower magnetic core 4.

  These stator cores are made of a green compact 6 in which an electromagnetic steel plate 5 is embedded. In this case, the magnetic flux flows from the permanent magnet 7 through the core to the other permanent magnet. The higher the magnetic flux density in the core, the smaller the shape of the device and the greater the torque. The magnetic flux density of 10,000 A / m is about 1.68 T for the powder magnetic core, 1.80 T for the magnetic steel sheet (35A210), and it is preferable to use the magnetic steel sheet for the magnetic core. However, in the case of a three-dimensional shape, it is difficult to fill a limited complex space with electromagnetic steel sheet pieces, and a powder magnetic core is used to overcome this.

  In the motor of the present invention, the space that cannot be filled with the electromagnetic steel sheet is made up with a magnetic powder. Moreover, if the magnetic steel sheet disposed in parallel with the flow of magnetic flux is interrupted, the magnetic permeability and the magnetic flux density are lowered. Therefore, it is preferable that the magnetic steel sheet embedded in the magnetic powder is continuous in parallel with the flow of magnetic flux. When the magnetic flux flows in a curved line, the magnetic steel sheet is also bent according to the curved line so as not to lower the magnetic permeability. As for problems other than magnetic characteristics, when the rotor rotates, if the permeability between the teeth and the slot changes abruptly, the torque varies greatly, and vibration is likely to occur. In this case, if the gap between the electromagnetic steel plate and the rotor in the core made of magnetic powder is increased sequentially from the center of the teeth, the cogging torque is reduced.

  When a prototype was manufactured with an actual φ300 mm × 100 mm axial motor, the efficiency of the motor was improved by 1.3% by embedding the magnetic steel sheet in the magnetic powder. Furthermore, when the magnetic steel sheet was configured to be parallel to the direction in which the magnetic flux flows, an improvement of 0.5% was observed. The noise is a structure where the distance from the rotor is doubled as it goes to the edge in the radial direction, rather than being evenly distributed on the rotor facing surface of the tooth part, and the torque ripple is 30.5% to 16.1% It was possible to reduce it.

  Next, the present invention will be further described based on examples.

  Here, the torque ripple is a quantitative expression of torque fluctuation that occurs when the rotor rotates, and means the ratio of the fluctuation to the average torque. In addition, magnetic powder is ferromagnetic powder, specifically granular soft powder such as pure Fe powder, Fe-Si, Fe-Si-Al, Fe-Ni, amorphous, nanocrystal (nanocrystalline alloy). These are made of magnetic powder and the surfaces thereof are electrically insulated. Further, the lubricant is used for promoting the movement so that the filling rate of the magnetic powder is high at the time of pressing so as not to form a gap. Specifically, fatty acids such as stearic acid and oleic acid can be used.

  A motor was manufactured by using the stator 2 that satisfies the conditions of the present invention for the 3-slot / 4-pole axial motor shown in FIG. In the core shown in FIG. 1 described above, the upper magnetic core has windings arranged along the upper magnetic core 3, and the lower magnetic cores all have windings arranged along the lower magnetic core 4. Therefore, the winding structure can be distributed and arranged in two stages only by arranging the windings in the upper magnetic core and the lower magnetic core.

  The upper magnetic core and the lower magnetic core are integrated by magnetic powder, and the electromagnetic steel sheet 5 is arranged in parallel to the direction in which the magnetic flux flows as shown by the dotted line in FIG. These electromagnetic steel sheets are also connected to the upper and lower parts, and are arranged in parallel with the direction in which the magnetic flux flows so as to be arranged inside the coil. Therefore, by providing a winding on the core to form an armature and disposing the rotor 1 on at least one of the lower side and the upper side, a large amount of magnetic flux generated by the armature can be given to the rotor. This improves driving efficiency when relative driving is performed between the armature and the rotor.

  The tooth surface has a structure in which the distance from the rotor is separated from 0.3 to 2 times the gap distance as it goes to the edge in the radial direction, rather than the one in which the tip of the electromagnetic steel sheet is arranged at a uniform height. Torque ripple is suppressed and a motor with low noise can be produced.

  Tables 1 and 2 show the results of comparison between a motor using a magnetic core prepared based on this example and a motor using a conventional dust core. By using a magnetic core that satisfies the conditions defined in the present invention, high efficiency and low noise of the motor can be achieved.

The second embodiment will be described below with reference to the drawings.
As shown in FIG. 1, an 18-slot claw pole type motor with a larger number of slots was used, and a motor was manufactured using a stator that satisfied the conditions of the present invention. The stator shown in FIG. 2 also includes an A stator ring 8 and a B stator ring 9 in a shape in which the inside is formed of an electromagnetic steel plate and the periphery thereof is enclosed by a green compact. In the meantime, a U-phase coil and a V-phase coil are provided. The A stator ring and the B stator ring are overlapped in the L direction of the axis.

  The inner end of the stator ring is T-shaped and extends to both sides of the axis in the L direction while being tapered. An electromagnetic steel plate 11 is disposed inside a tooth 10 formed of magnetic powder. A portion corresponding to the height in the radial direction of the coil is provided on the outside of the tooth. Become. Here, the pole means a magnetic pole in which magnetic flux is generated toward the rotor.

  As apparent from FIG. 2, the A stator ring 8 is a mirror-symmetrical member with respect to the B stator ring 9, and has the same shape that can be interchanged with the B stator ring by turning it over.

  The motor of this embodiment operates with a two-phase alternating current, and the U-phase and V-phase poles are arranged with an electrical angle shifted by 90 ° in the circumferential direction. On the other hand, each permanent magnet of the rotor is shared by the U-phase and V-phase poles and generates the same phase magnetic flux. Thereby, the pole of each phase can generate a uniform torque in the rotor.

  In the A stator ring 8 and the B stator ring 9, the electromagnetic steel plate 11 is arranged in parallel to the direction in which the magnetic flux flows as shown in FIG. These electromagnetic steel sheets are covered with magnetic powder and constitute one ring. Therefore, by providing a winding on the core to form an armature and disposing the rotor inside the ring, a large amount of magnetic flux generated by the armature can be given to the rotor. This improves driving efficiency when relative driving is performed between the armature and the rotor.

  As for the surface of the teeth 9, a structure in which the distance from the rotor is set to be twice the gap as it goes to the edge in the radial direction is used rather than a structure in which the tips of the electromagnetic steel plates are arranged at a uniform height. By doing so, torque ripple is suppressed and a motor with low noise can be produced.

  Tables 3 and 4 show the results of comparison between a motor using a magnetic core prepared based on this example and a motor using a conventional dust core. By using a magnetic core that satisfies the conditions defined in the present invention, high efficiency and low noise of the motor can be achieved.

It is a figure which shows an example at the time of applying this invention to an axial type motor. It is a figure which shows an example at the time of applying this invention to a claw pole type | mold motor. It is a figure which shows the electromagnetic steel plate arrange | positioned inside the teeth and pole of a stator ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor 2 Stator 3 Upper magnetic core 4 Lower magnetic core 5 Magnetic steel sheet 6 Magnetic powder compact 7 Permanent magnet 8 A Stator ring 9 B Stator ring 10 Teeth 11 Electrical steel sheet 12 Pole

Claims (3)

  A motor using a magnetic core formed by arranging an electromagnetic steel plate so as to follow a direction in which a magnetic flux flows and enclosing the electromagnetic steel plate with magnetic powder and a lubricant.   In the magnetic core, the stator structure is a three-dimensional structure, the magnetic steel sheet is arranged along the flow direction of the magnetic flux without being cut halfway, and a magnetic core formed by wrapping the magnetic steel sheet with magnetic powder and a lubricant is used. The motor according to claim 1, wherein the motor is a stator.   3. The motor according to claim 1, wherein in the magnetic core, the gap between the rotor and the teeth of the electromagnetic steel sheet disposed at the tip of the teeth is sequentially increased with respect to the rotation direction of the rotor.

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