JP2006238661A - Dc brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC brushless motor for realizing a long life and quietude while the body is made small. <P>SOLUTION: The DC motor includes a cup-shaped rotor 1 made up of a rotor hub 2 and a rotor yoke 3, in which a magnet 4 is provided on its circumferential face, and supported in a rotatable way with a center of a shaft 6 and a stator housing 9 for supporting the rotor 1 in a rotatable way. In addition, the DC motor has a structure for assembling a stator core 10 and a motor board 11 in the stator housing 9. At least one of a first bearing 14 and a second bearing 15 provided at the stator housing 9 for supporting the rotor 1 is an anti-friction bearing with an outer diameter larger than a shaft hole diameter of the stator core 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a DC brushless motor used for driving a disk of an optical apparatus such as a projector.

  Optical discs such as projectors and optical discs and other disk drive devices that display color images on a screen through light emitted from a light source through an RGB (W) color wheel (glass disc) are driven at high speed. An outer rotor type DC brushless motor is used as a drive source.

  An example of this DC brushless motor will be described with reference to FIG. In the rotor 51 formed in a cup shape in FIG. 3A, a rotor hub 53 is fixed to a shaft 52, and a rotor yoke 54 is bonded to the rotor hub 53. A magnet 55 is provided on the inner wall surface of the rotor yoke 54. A disk such as a color wheel (not shown) is mounted on the upper surface of the rotor hub 53.

Roller bearings (bearings) 58 and 59 are inserted into both end sides of the shaft hole 57 of the stator housing 56. The shaft 52 is inserted into bearings 58 and 59 and is rotatably supported. A snap ring 60 is attached to the end of the shaft 52 through which the bearing 59 is inserted. The stator housing 56 and the bearing 59 are provided with a disc spring 61 to urge the shaft 52 downward in the axial direction. The stator 62 is provided on the outer peripheral side of the stator housing 56. The stator 62 is assembled by inserting a stator core 65 around which a stator coil 64 is wound around a tooth portion 63 into a stator housing 56 (see Patent Documents 1 and 2). A fixed plate 66 is fixed to the outer periphery of the stator housing 56, and a motor board 67 is fixed to the fixed plate 66.
Japanese Patent Laid-Open No. 5-22918 JP-A-8-249807

However, with the downsizing of optical devices and drive devices, the motor diameter is also reduced to, for example, about φ14 mm. Therefore, the bearing that supports the shaft is also required to be downsized (for example, a bearing outer diameter of 5 mm or less for a motor diameter of 14 mm). In particular, in FIG. 3B, since the bearing 58 is inserted into the shaft hole 57 of the stator housing 56 and is smaller than the inner diameter of the stator core 65, the life of the bearing 58 is shortened and noise is increased. There is.
Further, in order to maintain the strength of the bearing 58, it is necessary to use a bearing having a large outer diameter, and the inner diameter of the stator core 65 is increased. For this reason, with the miniaturization of the motor, there is a problem that the number of turns of the coil 64 wound around the tooth portion 63 is reduced and a necessary rotational torque cannot be obtained.
In particular, video equipment and audio equipment are often used continuously for a long time, and there is a high demand for improving the quietness while extending the life of the motor.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a DC brushless motor capable of reducing the size of the motor and realizing a longer life and quietness.

In order to achieve the above object, the present invention comprises the following arrangement.
A rotor hub and a rotor yoke that is provided with a magnet on the inner peripheral surface and formed in a cup shape and supported rotatably around a shaft, a stator housing that rotatably supports the rotor, a stator core and a motor board on the stator housing In the DC brushless motor having a structure in which the bearing is assembled, at least one of the first and second bearings provided in the stator housing is provided with a rolling bearing having an outer diameter larger than the inner diameter of the stator core.
Further, the first and second bearings are provided on both sides in the axial direction of the stator core assembled to the stator housing.
Further, the first bearing provided between the stator housing and the rotor hub has an outer diameter larger than the inner diameter of the stator core.
Furthermore, the second bearing provided between the stator housing and the shaft is secured in the axial direction, and the shaft is biased in the axial direction toward the motor substrate.

If the DC brushless motor described above is used, at least one of the first and second bearings provided in the stator housing is provided with a rolling bearing having an outer diameter larger than the inner diameter of the stator core. Since the bearing supporting the shaft has an outer diameter that is not limited by the inner diameter of the stator core, the bearing strength does not decrease, and a long life and quietness can be realized even with a small motor.
In addition, the first and second bearings are provided on both sides in the axial direction of the stator core assembled to the stator housing, so that the stator housing to which the stator core is assembled has a small diameter so that the number of windings wound around the tooth portion can be reduced. The torque characteristic can be improved by increasing.
Specifically, since the first bearing provided between the stator housing and the rotor hub has an outer diameter larger than the inner diameter of the stator core, the bearing strength against the rotational load of the rotor can be improved.

  Hereinafter, the best embodiment of a DC brushless motor according to the present invention will be described with reference to the accompanying drawings. The DC brushless motor of this embodiment includes a rotor that is rotatably supported around a shaft, a stator housing that rotatably supports the rotor with respect to a fixed plate, and a stator in which a stator core and a motor board are assembled to the stator housing. Widely applicable to motors equipped. In this embodiment, a DC brushless motor for driving an optical device such as a projector will be described as an example.

With reference to FIG.1 and FIG.2, schematic structure of a DC brushless motor is demonstrated.
In FIG. 1, a rotor 1 is formed in a cup shape by, for example, a cylindrical rotor yoke 3 made of a magnetic material being bonded to the peripheral surface of a rotor hub 2 on which a color wheel is mounted. On the inner peripheral surface of the rotor yoke 3, a cylindrical magnet 4 that is alternately magnetized in the circumferential direction to N pole / S pole is provided. The rotor yoke 3 may be integrally assembled with the rotor hub 2 by caulking. However, in consideration of the influence on the bearing due to vibration and the influence of the distortion of the rotor 1, adhesion is preferable.
A step portion 5 is formed in the circumferential direction on the circumferential surface of the rotor hub 2. The step portion 5 is provided with a balance weight as required. One end of a shaft 6 is press-fitted into the shaft hole of the rotor hub 2, and the rotor 1 is supported so as to be rotatable around the shaft 6.

  Next, the configuration of the stator 7 will be described. In FIG. 1, a stator housing 9 made of a nonmagnetic material supports the rotor 1 in a rotatable manner. A stator core 10 and a fixed plate 8 are assembled on the outer peripheral side of the stator housing 9. A coil winding 12 is wound around the stator core 10 via an insulating member (insulating paint, insulator, etc.) around a tooth portion 10a (see FIG. 2B). The stator core 10 is assembled integrally by inserting the through hole 10b into the stator housing 9. The motor substrate 11 is supported by the fixed plate 8, and a flexible cable 13 is connected to the motor substrate 11.

  The stator housing 9 has a first bearing (rolling bearing) 14 on the outer periphery on one end side (upper side in FIG. 1) and a second bearing (rolling bearing) 15 on the inner periphery on the other end side (lower side in FIG. 1). Has been inserted. The first and second bearings 14 and 15 are provided on both sides in the axial direction of the stator core 10 assembled to the stator housing 9. Specifically, the first bearing 14 is provided between the stator housing 9 and the rotor hub 2. The second bearing 15 is provided between the stator housing 9 and the shaft 6. Thereby, by making the stator housing 9 to which the stator core 10 is assembled into a small diameter, the number of turns of the coil winding 12 wound around the tooth portion 10a can be increased and the torque characteristics can be improved.

  A snap ring 16 is fitted into the other end side of the shaft 6 (the lower side in FIG. 1), and the second bearing 15 is prevented from being pulled out in the axial direction. Further, the second bearing 15 is urged toward the other end in the axial direction (the lower side in FIG. 1) by a coil spring 17 provided between the second bearing 15 and the stator housing 9. For this reason, the shaft 6 is always urged in the axial direction toward the fixed plate 8 (motor substrate 11).

  Here, an example of the assembly structure of the DC brushless motor described above will be described with reference to FIG. The stator housing 9 is assembled with a fixed plate 8 to which the motor substrate 11 is fixed. The stator core 10 is assembled to the upper side of the motor substrate 11 (fixed plate 8) through the through hole 10b of the stator core 10 from the upper end side of the stator housing 9. Further, the first bearing 14 is assembled to the outer periphery on the upper end side of the stator housing 9. As shown in FIG. 2B, the outer diameter of the first bearing 14 is larger than the inner diameter (through hole diameter) of the stator core 10.

  In FIG. 2A, the color wheel 18 is integrally assembled on the upper surface of the rotor hub 2 of the rotor 1. The shaft 6 of the rotor 1 is inserted into the shaft hole 9a of the stator housing 9 from the upper end opening. A coil spring 17 and a second bearing 15 are inserted into a lower end side opening 9b communicating with the shaft hole 9a of the stator housing 9, and the shaft 6 is assembled through these. A snap ring 16 is fitted into a groove 6a provided at the end of the shaft 6 to prevent it from coming off. The shaft 6 is always urged downward by the elastic force of the coil spring 17.

  As described above, the first bearing 14 is a bearing having an outer diameter larger than the inner diameter of the stator core 10. As a result, even if the motor is downsized, the first bearing 14 that supports the rotor 1 can employ a bearing having an outer diameter that is not restricted by the inner diameter restriction of the stator core 10. Long life and quietness can be realized.

  The DC brushless motor is exemplified by the motor for driving the projector, but is not limited to this, and the motor for other uses such as a disk driving motor for FD, CD, CD-R, CD-RW, DVD, etc. It may be.

It is sectional drawing of a DC brushless motor. FIG. 4 is an exploded sectional view of a DC brushless motor and a plan view showing a relationship between a bearing outer diameter and a stator core inner diameter. It is a sectional view of a conventional DC brushless motor and a plan view showing the relationship between the bearing outer diameter and the stator core inner diameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotor hub 3 Rotor yoke 4 Magnet 5 Step part 6 Shaft 6a Groove 7 Stator 8 Fixed plate 9 Stator housing 9a Shaft hole 9b Opening part 10 Stator core 11 Motor board 12 Coil winding 13 Flexible cable 14 First bearing 15 Second bearing 15 Bearing 16 Snap ring 17 Coil spring 18 Color wheel

Claims (4)

A rotor formed in a cup shape by a rotor hub and a rotor yoke provided with a magnet on the inner peripheral surface, and supported rotatably around a shaft;
In a DC brushless motor having a stator housing that rotatably supports a rotor, and a structure in which a stator core and a motor board are assembled to the stator housing,
A DC brushless motor characterized in that at least one of the first and second bearings provided in the stator housing is provided with a rolling bearing having an outer diameter larger than the inner diameter of the stator core.   2. The DC brushless motor according to claim 1, wherein the first and second bearings are provided on both sides in the axial direction of the stator core assembled to the stator housing.   The DC brushless motor according to claim 1, wherein the first bearing provided between the stator housing and the rotor hub has an outer diameter larger than an inner diameter of the stator core.   2. The DC bearing according to claim 1, wherein the second bearing provided between the stator housing and the shaft is retained in the axial direction, and the shaft is biased in the axial direction toward the motor substrate. Brushless motor.

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