JP4005670B2 - Axial fan motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brushless motor used for a circumferentially opposed axial fan motor and a CPU cooling fan motor used for cooling a small electric device such as a notebook computer.
[0002]
[Prior art]
Conventionally, various types of axial fan motors are known. FIG. 3 is a side sectional view showing an example of the configuration of a conventional axial fan motor.
[0003]
In FIG. 3, a cylindrical bush 7 made of an iron-based material is insert-molded in an upright state on the bottom plate portion of the housing 1 constituting the main body of the axial fan motor. A circuit board 2 on which a circuit for performing switching control of the coil 5 and the like is mounted is inserted into the outer periphery of the bush 7. On the upper surface of the circuit board 2, a first stator yoke 4 made of an iron-based material and a coil 5 constituting a stator of the motor are placed while being inserted along the outer periphery of the bush 7. After the circuit board 2, the first stator yoke 4, and the coil 5 are inserted into the outer periphery of the bush 7, the disc-shaped second stator yoke 6 is press-fitted into the upper end portion of the bush 7, whereby the circuit board 2, The first stator yoke 4 and the coil 5 are fixed to the bottom plate portion of the housing 1.
[0004]
On the other hand, a ball bearing 9 is press-fitted or inserted into the upper part inside the bush 7, and the outer ring is supported by a stepped portion 7 a formed on the inner peripheral surface of the substantially central portion in the height direction of the bush 7. . A sleeve metal 8 is press-fitted under the stepped portion 7a. A shaft 10 is integrally fixed by insert molding to a rotor 11 made of a resin material in which blades constituting a fan are integrally formed. The shaft 10 is inserted into a ball bearing 9 and a sleeve metal 8. A support surface 11 a is formed at the center of the rotor 11 and is placed on the upper surface of the inner ring of the ball bearing 9. With these configurations, the rotor 11 is supported rotatably with respect to the bush 7. A cut washer 14 is attached to the lower end portion of the shaft 10 so that the shaft 10 does not come out upward. A permanent magnet 12 with a predetermined magnetization is fixed to the inner peripheral surface of the rotor 11, and the rotor (blade) 11 is driven to rotate in accordance with the magnetic field generated by the coil 5.
[0005]
[Problems to be solved by the invention]
In the conventional axial fan motor configured as described above, the permanent magnet 12 of the rotor 11 includes the upright portion 4a of the first stator yoke 4 and the upright portion 6a of the second stator yoke 6 made of iron or silicon steel plate material. Thus, as shown by an arrow A, the suction is performed obliquely downward, so that the support surface 11a of the rotor 11 acts to push down the inner ring of the ball bearing 9 and apply a preload to the bearing 9 by this suction force.
[0006]
However, since the vertical component of the force of the upright portion 4a of the first stator yoke 4 and the upright portion 6a of the second stator yoke attracting the permanent magnet 12 is relatively small, sufficient preload cannot be applied to the ball bearing 9 and vibration occurs. In addition, there is a problem that noise increases.
[0007]
As a method for solving this problem, there is known a method in which donut-shaped or C-shaped rubber is attached between the cut washer 14 and the lower surface of the sleeve metal 8 as shown in FIG. It has been. According to this method, an appropriate preload can be applied to the ball bearing 9. However, since materials such as rubber are easily deteriorated and deteriorated and are easily scraped by rotational friction with the washer 14, there is a problem that the life is short.
[0008]
Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a brushless motor that can apply an appropriate preload to a ball bearing and has a long life.
[0009]
[Means for Solving the Problems]
To solve the above problems and achieve the object, an axial fan motor according to the present invention, the coil is arranged on the stator side, the axial flow fan is a permanent magnet rotor side blade is integrated is arranged In the motor, a bearing for rotatably supporting the rotor, a circuit board disposed on the stator so as to be positioned immediately below the permanent magnet, and a magnetic body provided so as to be in contact with the upper surface of the circuit board The rotor-side permanent magnet is attracted by the attraction member, and the bearing is preloaded by the attraction force.
[0010]
In the axial fan motor according to the present invention, the suction member is made of a disk-shaped magnetic body.
[0011]
In the axial fan motor according to the present invention, the suction member is made of a silicon steel plate or an iron plate.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0013]
FIG. 1 is a side sectional view showing an example in which a brushless motor according to an embodiment is applied to an axial fan motor.
[0014]
In FIG. 1, a cylindrical bush 37 made of an iron-based material is insert-molded in an upright state on a bottom plate portion of a synthetic resin casing 31 constituting the main body of the axial fan motor 50. . A circuit board 32 on which a circuit for performing switching control of the coil 35 and the like is mounted is inserted into the outer periphery of the bush 37. On the upper surface of the circuit board 32, a suction member 33, which is a characteristic structural member of the present invention, is formed by processing a silicon steel plate or an iron plate into a ring shape. The operation of the suction member 33 will be described later. On the upper surface of the suction member 33, a first stator yoke 34 made of an iron-based material and a coil 35, which constitutes the stator of the motor, are placed while being inserted along the outer periphery of the bush 37. . The circuit board 32, the suction member 33, the first stator yoke 34, and the coil 35 are inserted into the outer periphery of the bush 37, and then the ring-shaped second stator yoke 36 is press-fitted into the upper end portion of the bush 37. The substrate 32, the suction member 33, the first stator yoke 34, and the coil 35 are fixed to the bottom plate portion of the housing 31.
[0015]
On the other hand, a ball bearing 39 is press-fitted or inserted into the upper part inside the bush 37, and the outer ring is supported by a stepped portion 37 a formed on the inner peripheral surface of the substantially central portion in the height direction of the bush 37. . A sleeve metal 38 is press-fitted under the stepped portion 37a. A shaft 40 is integrally fixed by insert molding to a rotor 41 made of a resin material in which blades constituting a fan are integrally formed. The shaft 40 is inserted into a ball bearing 39 and a sleeve metal 38. A support surface 41 a is formed at the center of the rotor 41 and is placed on the upper surface of the inner ring of the ball bearing 39. With these configurations, the rotor 41 is rotatably supported with respect to the bush 37. Further, a cut washer 44 is attached to the lower end portion of the shaft 40 so that the shaft 40 does not come out upward. A rotor yoke 43 and a permanent magnet 42 having a predetermined magnetization are fixed to the inner peripheral surface of the rotor 41, and the rotor (blade) 41 is driven to rotate according to the magnetic field generated by the coil 35.
[0016]
FIG. 2 is a perspective view showing a state in which the housing 31, the circuit board 32, the suction member 33, and the first stator yoke 34 are disassembled.
[0017]
As shown in FIG. 2, the circuit board 32, the suction member 33, and the first stator yoke 34 are inserted into the housing 31 from above and assembled. The circuit board 32 is provided with a hall element 45 for detecting the switching timing of the coil.
[0018]
In the axial fan motor 50 configured as described above, the height direction center of the permanent magnet 42 of the rotor 41 is set to a position higher than the height direction centers of the first stator yoke 34 and the second stator yoke 36. Therefore, the permanent magnet 42 is attracted diagonally downward as shown by the arrow B in FIG. 1 by the upright portion 34a of the first stator yoke 34 and the upright portion 36a of the second stator yoke 36 made of iron-based material. Is done. For this reason, the support surface 41 a of the rotor 41 acts to push down the inner ring of the ball bearing 39 and apply a preload to the bearing 39 by this suction force. At the same time, in the present embodiment, the permanent magnet 42 is attracted downward as indicated by the arrow C by the attraction member 33, and the bearing 39 is also preloaded by this attraction force. Therefore, the combined force of the suction force of the first stator yoke 34 and the second stator yoke 36 and the suction force of the suction member 33 acts as a force for applying a preload to the bearing 39, and a sufficient preload can be applied to the bearing 39. As a result, the rotation of the rotor 41 is stabilized.
[0019]
As described above, according to the present embodiment, the preload applied to the inner ring of the bearing can be increased by sucking the rotor with the suction member installed below the stator, thereby stabilizing the ball inside the bearing. It can be rotated in the state. Thereby, vibration and noise can be reduced.
[0020]
In addition, since a material that easily deteriorates such as rubber is not used, the life of the bearing can be extended.
[0021]
Furthermore, since the silicon steel plate or the iron plate is used as the suction member in contact with the substrate, the heat dissipation of the motor itself can be improved.
[0022]
Note that the present invention can be applied to modifications or variations of the above-described embodiment without departing from the spirit of the present invention.
[0023]
【The invention's effect】
As described above, according to the present invention, the preload applied to the inner ring of the bearing can be increased by sucking the rotor with the suction member installed below the stator, and the ball inside the bearing is stabilized. It can be rotated in the state. Thereby, vibration and noise can be reduced.
[0024]
In addition, since a material that easily deteriorates such as rubber is not used, the life of the bearing can be extended.
[0025]
Furthermore, since the silicon steel plate or the iron plate is used as the suction member in contact with the substrate, the heat dissipation of the motor itself can be improved.
[0026]
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an example in which a brushless motor according to an embodiment is applied to an axial fan motor.
FIG. 2 is a perspective view showing a state in which a housing, a circuit board, a suction member, and a first stator yoke are disassembled.
FIG. 3 is a side sectional view showing an example of the configuration of a conventional axial fan motor.
FIG. 4 is a side sectional view showing another example of the configuration of a conventional axial fan motor.
[Explanation of symbols]
31 Housing 32 Circuit board 33 Suction member 34 First stator yoke 35 Coil 36 Second stator yoke 37 Bush 38 Sleeve metal 39 Ball bearing 40 Shaft 41 Rotor 42 Permanent magnet 43 Rotor yoke 44 Cut washer

Claims (3)

In an axial fan motor in which a coil is arranged on the stator side and a permanent magnet is arranged on the rotor side where the blades are integrated ,
A bearing that rotatably supports the rotor;
A circuit board disposed on the stator so as to be located immediately below the permanent magnet ;
An attraction member made of a magnetic material provided in contact with the upper surface of the circuit board ;
An axial fan motor characterized in that the permanent magnet on the rotor side is attracted by the attraction member and preload is applied to the bearing by the attraction force. The axial flow fan motor according to claim 1, wherein the suction member is made of a disk-shaped magnetic body. 3. The axial fan motor according to claim 2, wherein the suction member is made of a silicon steel plate or an iron plate.

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