JP6311997B2 - Outer rotor type motor - Google Patents

Description

  The present invention relates to a motor, and more particularly to an outer rotor type motor.

  In the conventional outer rotor type motor, the core press-fitted portion of the bearing housing receives stress when the stator core is press-fitted into the bearing housing. As the outer diameter of the bearing housing is subjected to stress, the inner diameter is elastically deformed. As a result, the stress is transmitted, and the inner diameter of the bearing held in the bearing housing is also reduced compared to the range where the stator core is not press-fitted because the portion into which the stator core is press-fitted is deformed.

  This causes a problem that the cylindrical accuracy of the inner diameter of the bearing is deteriorated and the shaft swing is increased. Further, in a structure having an outer rotor type oil-impregnated bearing, vibration generated in the stator core propagates to the bearing and the shaft through a bearing housing (for example, made of brass) to generate noise and load vibration.

  On the other hand, for example, in Patent Document 1, the inner diameter side of the portion where the stator core is pressed into contact with the outer diameter of the bearing housing is formed in a concave shape so as not to contact the bearing. Further, in Patent Document 2, the bearing housing has a bent structure, and has a structure in which a distance is provided between an inner diameter side where the bearing contacts and an outer diameter side where the stator core contacts.

  However, in Patent Document 1, the processing of the bearing housing is complicated (inner diameter side), which increases the cost. Further, it is necessary to narrow a portion where the bearing housing and the stator core are in contact with each other, and there is a problem that the holding strength of the stator core is weakened. In Patent Document 2, the inner diameter side and the outer diameter side are connected in the direction in which the stator core is inserted into the bearing housing, which causes deformation of the inner diameter.

JP 2003-244890 A JP 2003-339132 A

  The present invention has been made in view of such problems, and an object of the present invention is to provide an outer rotor type motor having a good bearing inner diameter dimensional accuracy.

The present invention is grasped by the following composition in order to achieve the above-mentioned object.
(1) A first aspect of the present invention is an outer rotor type motor, which is attached to a shaft, a bearing that rotatably supports the shaft, a bearing housing that holds the bearing, and the shaft. A rotor having a magnet on an inner peripheral surface, and a stator having a stator core press-fitted into the outer diameter of the bearing housing so as to face the magnet, and the bearing housing has an outer diameter into which the stator core is press-fitted. A gap is provided in the center of the meat between the inner diameter with which the bearing contacts.

(2) In the configuration of (1) above, the gap may have a length that is greater than or equal to the thickness of the stator core in the axial direction of the shaft.

(3) In the configuration of (1) or (2), the gap may have an opening on a side where the stator core is press-fitted.

  ADVANTAGE OF THE INVENTION According to this invention, the motor of an outer rotor type | mold with the favorable bearing internal-diameter dimensional accuracy can be provided.

1 is a cross-sectional view of an outer rotor type motor (spindle motor) according to an embodiment of the present invention. 1 is an exploded view of an outer rotor type motor (spindle motor) according to an embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. Note that the same number is assigned to the same element throughout the description of the embodiment.

<Basic structure of motor 1>
First, the configuration of an outer rotor type motor (hereinafter simply referred to as “motor 1”) will be described with reference to FIG. In the following, a spindle motor will be described as an outer rotor type motor. However, the present embodiment is not limited to a spindle motor, but can be applied to all outer rotor type motors.

  As shown in FIG. 1, the motor 1 mainly includes a shaft 10, a rotating rotor 20, and a stator 30 that interacts with the rotor 20 and generates a rotational moment. The shaft 10 is rotatably supported by a bearing 11, and the bearing 11 is held by a bearing housing 12. A disc-shaped sliding plate 13 for receiving the shaft 10 and a closing plate 14 covering the lower end portion of the bearing housing 12 are attached to the lower end of the bearing housing 12. As will be described later, the bearing housing 12 is provided with a gap 12a at a position corresponding to the press-fitted stator core 31.

  The rotor 20 includes a hub 21 fixed to the shaft 10 and a cylindrical rotor yoke 22 arranged so as to cover the outside of the stator 30. The rotor yoke 22 is connected to the shaft 10 via the hub 21, and the magnet 23 is disposed at a position facing the stator core 31 on the inner peripheral surface of the rotor yoke 22. The stator 30 includes a stator core 31 around which a coil 32 is wound, and is arranged around the bearing housing 12 in a rotationally symmetrical manner.

  In the motor 1, when the rotor 20 rotates about the shaft 10 as a rotation axis, the shaft 10 itself fixed to the hub 21 also rotates. Here, an oil-impregnated bearing can be used as the bearing 11, and lubricating oil (not shown) is injected between the shaft 10 and the bearing 11. In addition to this, a ball bearing or a fluid bearing may be used as the bearing 11 in applying the present embodiment. In the case of a hydrodynamic bearing, a herringbone-shaped or spiral-shaped dynamic pressure generating groove (not shown) is formed on the outer peripheral surface of the shaft 10 and / or the inner peripheral surface of the bearing 11, so that the lubricating oil has a dynamic pressure. It flows and presses according to the groove pattern of the generating groove, producing a local high-pressure part. As a result, the side surface of the rotating shaft 10 is supported by the bearing 11, and the bottom surface of the shaft 10 is supported by the sliding plate 13.

<Gap 12a of Bearing Housing 12>
The motor 1 is used when high-speed rotation is required, such as a polygon mirror scanner motor used in a laser writing system such as a digital copying machine or a spindle motor of an HDD. In the case of the polygon mirror scanner motor, it rotates at a high speed exceeding 40,000 times per minute, reflects the laser beam from the semiconductor laser, and transfers it to the photosensitive drum. In such a high-speed rotation, the cylindrical accuracy of the inner diameter of the bearing 11 is deteriorated and the vibration around the shaft 10 is increased. In addition, in the structure having the outer rotor type oil-impregnated bearing, the vibration generated in the stator core 31 is If it propagates to the bearing 11 and the shaft 10 through the bearing housing 12 to generate noise and load vibration, the influence is great.

  Therefore, in the present embodiment, attention is paid to a method in which the deformation of the bearing 11 (inclination toward the shaft 10 side) that occurs when the stator core 31 of the stator 30 is press-fitted into the bearing housing 12, and under the use conditions of high-speed rotation. The motor 1 which can suppress the above situations is also obtained. Hereinafter, this point will be described with reference to FIG.

  FIG. 2 shows an exploded view of the motor 1. The motor 1 is assembled by press-fitting or inserting the shaft 10 to which the stator core 31, the bearing 11, the washer 15, and the rotor 20 are attached sequentially into the bearing housing 12 at the lower end in the drawing. Although not shown, in order to adjust the rotational balance of the motor 1, a weight is formed on the upper surface of the rotor 20 in the case of positive balance adjustment and a round hole is formed in the case of negative balance adjustment as necessary. Stealing may be provided.

  The bearing housing 12 is made of non-ferrous metal or resin. In the case of non-ferrous metal, the lump is formed by cutting or the like, and in the case of resin, it is formed by injection molding. Here, as the nonferrous metal, for example, a copper alloy such as brass is preferably used.

  As shown in FIG. 2, the stator core 31 is press-fitted into the outer diameter side of the bearing housing 12 that holds the bearing 11 of the motor 1. In the bearing housing 12, a gap 12 a such as a slit is provided at the center of the meat between the outer diameter into which the stator core 31 is press-fitted and the inner diameter with which the bearing 11 is in contact. By providing the gap 12a, the deformation of the bearing housing 12 due to the press-fitting of the stator core 31 can be released by the gap 12a provided in the bearing housing 12 itself. Thereby, the deformation of the bearing housing 12 is not transmitted to the bearing 11, and the position of the bearing 11 can be arranged accurately and concentrically. Therefore, the inclination of the bearing 11 that affects the rotation of the shaft 10 can be prevented.

  The length of the gap 12a may be set to be equal to or greater than the thickness of the stator core 31 in the axial direction of the shaft 10, that is, equal to or greater than the thickness. Thereby, the deformation | transformation by press injection of the stator core 31 can be escaped still more reliably. Further, it is desirable that the gap 12a is formed with an opening on the side where the stator core 31 is press-fitted. Thereby, the press fit of the stator core 31 can be performed easily. Furthermore, it is desirable to form the gap 12a so as to have a narrow width in a range that can be processed. Thereby, the strength of the bearing housing 12 can be kept intact.

  As described above, the present invention is not limited to the specific embodiments but includes various modifications, which will be apparent to those skilled in the art from the description of the scope of claims. It is.

1. Motor (outer rotor type motor, spindle motor)
DESCRIPTION OF SYMBOLS 10 ... Shaft 11 ... Bearing 12 ... Bearing housing 12a ... Gap (slit)
13 ... sliding plate 14 ... closing plate 15 ... washer 20 ... rotor 21 ... hub 22 ... rotor yoke 23 ... magnet 30 ... stator 31 ... stator core 32 ... coil

Claims (1)

An outer rotor type motor,
A shaft,
A bearing that rotatably supports the shaft;
A bearing housing for holding the bearing;
A rotor attached to the shaft and having a magnet on the inner peripheral surface;
A stator having a stator core press-fitted into the outer diameter of the bearing housing so as to face the magnet,
The bearing housing, in the center of the meat between the stator core are in contact is the outer diameter and the bearing to be press-fitted inside diameter so as to be in close contact without any gap, have a slit miss deformation of the bearing housing by press-fitting of the stator core ,
The slit has a length greater than or equal to the thickness of the stator core in the axial direction of the shaft;
The motor according to claim 1, wherein the slit has an opening on a side into which the stator core is press-fitted .

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