JPH06261490A - Bearing unit for brushless motor - Google Patents

Abstract

PURPOSE:To provide an inexpensive bearing unit for lightweight downsized brushless motor in which vibration and jitter of shaft are eliminated by bearing radial load and thrust load of motor by means of two bearings. CONSTITUTION:Radial load of a motor is born by a sintered oil retaining metal 2 fixed to a stator member and a motor shaft 1 is supported rotatably through the sintered oil retaining metal. A thrust bearing is provided between the stator member and a rotor disposed oppositely thereto through balls for bearing thrust load. This structure provides a brushless motor in which the balls 14 rotate stably and vibration or jitter of the shaft is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device for a motor used in, for example, audio equipment, video equipment, office equipment, information equipment, and industrial equipment.

[0002]

2. Description of the Related Art In recent years, motors have become lighter, thinner, shorter, smaller, and have a long life and high reliability as the market for households and industries has expanded, and it is desired to develop an ultra-compact high-performance brushless motor instead of a brushed motor. Came. In particular, in the FDD device of the information storage device, with the spread of notebook-sized personal computers, the brushless motor as a driving component is also small, and the demand for a motor with a motor height of 10 mm to 3 mm has begun to emerge. Is becoming impossible.

An example of a conventional bearing device for an FDD spindle brushless motor will be described below with reference to the drawings.

(Conventional Example 1) FIG. 12 is a sectional view of an example of a bearing device of a conventional FDD brushless motor, and FIG. 13 is a sectional view of a motor using the bearing device of FIG.

In FIGS. 12 and 13, 21 is a motor shaft, 22 is a drive magnet, 23 is a rotor frame,
Reference numeral 24 is a set bearing, 24c is a spindle hub portion of the set bearing 24, 25 is a wettable sheet, 26 is a printed circuit board, 27 is a stay housing, 28 is a coil, and 29 is a drive pin.

The motor shaft 21 has N poles in the circumferential direction,
A rotor frame 23, to which a cylindrical drive magnet 22 having S poles alternately magnetized is fixed, is fixed via a spindle hub portion 24c, which is a component of the assembly bearing 24, and constitutes a rotating member (hereinafter referred to as a rotor). ing. A drive pin 29 for engaging the hub portion of the magnetic disk is provided on the rotor.

The printed circuit board 26 is insulated and adhered with the coils 28 radially arranged, and the stay housing 27 is fixed to form a fixing member (hereinafter referred to as a stator). The assembled bearing 24 is composed of an inner diameter portion 24a, a fixed portion 24b, a spindle hub portion 24c, two sets of balls, and two sets of retainers. The motor is an axial type brushless motor.

The operation of the motor bearing device having the above-described structure will be described below.

The rotor shaft 21 is inserted into the inner diameter portion 24a of the assembly bearing 24 so as to rotatably support the rotor, and the load in the thrust direction is received by the spindle hub portion 24c and the fixed portion 24b of the assembly bearing 24 via balls. ing. On the other hand, the radial load is the inner diameter portion 2 of the assembled bearing 24.
4a and the fixed portion 24b are received via balls.

First, when the coil 28 is energized, the rotor rotates due to magnetic attraction and repulsion with the drive magnet 22 fixed to the rotor. The rotor presses the rotor frame 23 against the assembled bearing 24 by the magnetic attraction force of the drive magnet 22 and the coil 28, and the thrust load receiving portion of the assembled bearing 24 receives the thrust load to prevent vibration and movement in the thrust direction.

The rotor prevents rotation in the radial direction caused by rotation by receiving a radial load at the radial load receiving portion of the assembly bearing 24, and supports the rotor rotatably.

(Conventional Example 2) FIG. 14 is a cross-sectional view of an FDD brushless motor using another conventional bearing device. FIG. 15 is a sectional view of another conventional bearing device in use.

In FIGS. 14 and 15, 31 is a motor shaft, 32 is a drive magnet, 33 is a rotor frame,
34 is a thrust bearing, 35 is a stopper ring, 36 is a printed circuit board, 37 is a stay housing, 38 is a coil,
39 is a stator core.

In the figure, a rotor frame 33 provided with a drive pin for engaging with a hub of a magnetic disk constitutes a spindle hub portion 33a of the rotor frame 33, and a motor shaft 31 as a rotating shaft is fixed to the center thereof. A frequency power generation magnet is attached to the outside of the cup-shaped portion of the rotor frame 33, and a drive magnet 32 is fixed to the inside thereof. In addition, the printed circuit board 36
A stator core 39, around which a coil 38 is wound, is arranged at a position facing the drive magnet 32 and constitutes a stator.

The thrust bearing 34 is composed of a movable wheel 34a, a retainer 34b, a ball 34c and a fixed wheel 34d. Since the movable wheel 34a is press-fitted into the motor shaft 31, when the rotor frame 33 rotates, the movable wheel 34a.
a also rotates together. Movable wheel 34a and ball 34
There are two contact points with c, 40a and 40b. The fixed ring 34d of the thrust bearing 34 is attached to the printed circuit board 36 via the stay housing 37, and the fixed ring 34d and the ball 34c have two contact points 40c and 40d. Since the rotor portion comes off in the axial direction, the stopper ring 35 is attached to the groove provided in the shaft 31 to suppress the movement of the rotor in the thrust direction, thereby achieving impact resistance.

[0016]

However, since the bearing assembly having the structure of the above-mentioned conventional example 1 is expensive and the ball receiving surface of the bearing needs to have high hardness, the spindle hub member is hardened with iron. It must be a material for the system. Further, since the rotor frame is fixed to the spindle hub portion by caulking and heat-treated, it is not quick and cracks easily occur in the caulking portion. Furthermore, there is no adjustment mechanism for assembling the distance from the printed circuit board surface to the wettable sheet surface within a certain tolerance.

Further, the thrust bearing in the configuration of the above-mentioned conventional example 2 is composed of the movable ring and the fixed ring subjected to the drawing process, and is cheaper than the assembled bearing of the conventional example 1. However, since the balls are in a rolling system with four-point contact, a sliding phenomenon occurs, and there is a problem in that in the case of an axial type spindle brushless motor with a large thrust load, the rotational torque in the bearing becomes large. On the other hand, although it can be used in the case of radial type spindle brushless motors with a small thrust load, when both types of rotor are tilted, the action of the force trying to return the rotor is weak,
Since the inclination is promoted, the rotor portions come into contact with each other.
Although the stopper ring prevents a large inclination, if the stopper ring comes into contact, the load fluctuation during rotation becomes large and the jitter of the motor is deteriorated.

The present invention solves the above-mentioned problems of the prior art, in which the load in the radial direction of the motor and the load in the thrust direction are received by the two bearings, and the balls interposed between the rotor and the stator rotate stably. However, it is an object of the present invention to provide a bearing device for a brushless motor that is light, thin, short, and small, and that can satisfy performances such as shaft runout and jitter at low cost.

[0019]

To achieve this object, a bearing device for a brushless motor according to the present invention receives a radial load of the motor by a sintered oil-impregnated metal attached to a stator member. The motor shaft is rotatably supported via. In addition, a ball bearing that receives a load in the thrust direction is provided between the rotor and the rotor that is disposed so as to face the stator member. The ball bearing that receives the thrust load does not have the four-point contact as in Conventional Example 2, but the contact points are reduced. It has a different structure.

[0020]

With this structure, the load in the radial direction of the motor and the load in the thrust direction are received by the two bearings, so that the ball bearings interposed between the rotor and the stator rotate stably without slippage, and The performance such as runout and jitter can be satisfied.

[0021]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an FDD brushless motor using the bearing device of the present invention, and FIG. 2 is a sectional view of the bearing device of the present invention.

1 and 2, 1 is a motor shaft,
2 is a sintered oil-impregnated metal, 3 is a bearing housing, 4 is a rotor frame, 5 is a spindle hub, 6 is a stay housing, 7 is a printed circuit board, 8 is a stator core, 9 is a coil, 10 is a drive magnet, 11 is a drive pin, 12 is a hub magnet, 13 is a frequency power generation magnet (hereinafter referred to as F
(Abbreviated as G magnet). Further, the thrust bearing includes 14 balls, 15 movable wheels, 16 fixed wheels, 17
It consists of a retainer.

A hub magnet 12 for magnetically attracting the disc hub is attached to the rotor frame 4, and a spindle hub 5 to which the attracted disc hub is attached and a wettable sheet is attached to the rotor frame 4. A drive pin 11 for rotating together with the motor is attached to the rotor frame 4 via a rotation lever. Since it is an FDD motor, the disk chucking is performed on the rotor frame 4 with the above configuration.

The rotor of the motor rotates about a motor shaft 1 fixed at the center of a spindle hub 5 to which a cup-shaped rotor frame 4 is caulked and fixed. Inside the hanging portion of the rotor frame 4, a cylindrical drive magnet 10 having N-pole and S-pole magnetized alternately in the circumferential direction is fixed, and an FG magnet 13 is attached to the outside thereof, which is used for frequency power generation. Magnetization (hereinafter abbreviated as FG magnetization) is applied. The rotation speed signal of the motor is obtained by the generator line element on the printed circuit board 7 facing the FG magnetized surface,
The constant speed rotation control of the motor is performed at pm, 360 rpm, or 600 rpm.

The stator of the motor comprises a stator core 8 insulated by electrodeposition coating, a coil 9 wound around the stator core 8, and a printed circuit board 7 on which the stator core 8 is mounted via a stay housing 6. .

The motor provided with the rotor and the stator is a radial type brushless motor, in which a current is passed through the coil 9 to generate a magnetic field in the salient poles of the stator core 8, and a magnetic field drive magnet facing the stator core 8. A torque is generated between 10 and 10 to rotate the rotor.

The bearing device of the radial type brushless motor is composed of the sintered oil-impregnated metal 2 and the thrust bearing 3, and its operation will be described below.

The sintered oil-impregnated metal 2 is press-fitted into the bearing housing 3 fixed to the printed circuit board 7, and the load in the radial direction of the motor is received by the sintered oil-impregnated metal 2 to rotatably support the motor shaft. .

A thrust bearing for receiving a thrust load is provided with a plurality of balls 14 interposed between the rotor and the stator of the motor, and the balls 14 and 1 are provided on the surface of the thrust bearing facing the balls 14 on the rotor side. A flat movable wheel 15 rolling at a point is provided, and a flat fixed wheel 16 rolling at a single point with the ball 14 is provided on the surface of the thrust bearing facing the ball 14 of the stator. Holds at intervals.

The contact pressure, the size of the contact surface, and the contact amount at the contact portion between the ball and the fixed ring can be calculated using the Herts elastic contact theory in the case of point contact.

The contact pressure and the size of the contact surface of the thrust bearing having no groove are as shown in FIG. The maximum contact pressure Pm is obtained by (Equation 1).

[0033]

[Equation 1]

However, Pm: maximum contact pressure a: variable given from an auxiliary variable R: sum of curvatures of contact points Q: maximum rolling element load applied to the contact portion (Equation 1) can be converted into (Equation 2).

[0035]

[Equation 2]

According to JIS, the Pm of the thrust bearing is 4.
Since it is 2 MPa, it is used as a shape factor for calculating Q and calculating the basic dynamic load rating. The basic dynamic load rating Cam of the single-row grooved thrust bearing can be obtained by (Equation 3) due to recent improvements in materials and the like.

[0037]

[Equation 3]

However, f: coefficient of curvature of groove, coefficient determined by material, etc. Z: number of balls D: ball diameter Since the shape factor differs depending on the shape with grooves, the basic dynamic load rating with general grooves has a shape coefficient ratio Correcting. For the basic dynamic load rating Ca of the bearing of the desired shape, if the correction coefficient for the shape is k,

[0039]

[Equation 4]

It becomes The life Ln (H) is obtained by substituting the basic dynamic load rating Ca obtained in (Equation 4) into (Equation 5).

[0041]

[Equation 5]

However, n: rotational speed (rpm) Ca: basic dynamic load rating Ca (kgf) P: thrust load load (kgf) 12.5 mm of the thrust bearing of the first embodiment used for the height FDD spindle motor The relationship between the thrust load P and the life Ln is as shown in FIG. 4, and it can be seen that the radial type motor has a thrust load of about 0.6 kgf, which is sufficient reliability.

If a cylindrical portion is provided outside the fixed ring in the embodiment to prevent the grease from scattering due to rotation, the life is further extended.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

In FIG. 5, 1 is a motor shaft, 2 is a sintered oil-impregnated metal, 4 is a rotor frame, 5 is a spindle hub, 6 is a stay housing, and 7 is a printed circuit board.
The above is the same as the configuration of FIG. 2 is different from the configuration of FIG.
Is fixed, and the fixed ring 16 is fixed to the stator.

The operation of the bearing device for a motor constructed as described above will be described below.

Between the rotor and the stator of the motor, a plurality of balls 14 held by a retainer 17 at equal intervals.
A thrust bearing that receives a thrust load is provided with the rotor 14 interposed therebetween, and a movable wheel 15 that makes rolling contact with the ball 14 at one point is provided on the surface of the thrust bearing that faces the ball 14 on the rotor side. Further, the fixed ring 16 is bent in the axial direction to provide a cylindrical portion 16a, and the sintered oil-impregnated metal 2 is press-fitted to the cylindrical portion 16a so that the radial load of the motor is received by the sintered oil-impregnated metal 2. The motor shaft 1 is rotatably supported. Further, a cylindrical portion 16b is also provided on the outer peripheral portion of the fixed ring 16 having the inner peripheral cylindrical portion 16a, and the outer peripheral cylindrical portion 1 of the fixed ring is attached to the stay housing 6 mounted and fixed to the printed circuit board 7.
Fix 6b. The fixed ring 16 makes rolling contact with the ball 14 at one point.

Since the life of the thrust bearing increases as the ball diameter increases, the maximum ball diameter that can be configured is used.

As described above, according to the present embodiment, the bearing portion that controls the motor height is not the double structure of the printed circuit board 7 and the fixed ring 16 of the stator but the fixed ring 16, and the plate thickness of the printed circuit board 7 is not limited. The diameter of the ball can be increased by the amount of reduction, and a bearing device for a radial type brushless motor that has a long life and is light, thin and short can be realized.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

In FIG. 6, 1 is a motor shaft, 2 is a sintered oil-impregnated metal, 4 is a rotor frame, 5 is a spindle hub, 6 is a stay housing, and 7 is a printed circuit board.
The above is the same as the configuration of FIG. 2 and FIG. Figure 2
5 is different in that the sintered oil-impregnated metal 2 is fixed to the fixed ring 16 of the thrust bearing and the fixed ring is fixed to the stator, and the point different from the configuration in FIG. 5 is that the fixed ring has two balls. It is a point that is transposed at a point.

The operation of the motor bearing device constructed as described above will be described below.

Between the rotor and the stator of the motor, a plurality of balls 14 held by a retainer 17 at equal intervals.
A thrust bearing that receives a thrust load is provided with the rotor 14 interposed therebetween, and a movable wheel 15 that makes rolling contact with the ball 14 at one point is provided on the surface of the thrust bearing that faces the ball 14 on the rotor side.

Further, the fixed ring 16 is axially bent to form a cylindrical portion 16a, and the sintered oil-impregnated metal 2 is press-fitted into the cylindrical portion 16a to load the radial load of the motor on the sintered oil-impregnated metal 2. The motor shaft 1 is rotatably supported. The cylindrical portion 16b is also provided on the outer peripheral portion of the fixed ring having the inner peripheral cylindrical portion, and the outer peripheral cylindrical portion 16b of the fixed ring is fixed to the stay housing 6 mounted and fixed to the printed circuit board 7. The inner peripheral cylindrical portion 16a and the ball 14 roll at one point,
Since the flat portion of the fixed ring 16 and the ball 14 make rolling contact at one point, the fixed ring 16 makes rolling contact with the ball at two points. Fixed wheel 16
The sintered oil-impregnated metal 2 is press-fitted into the inner cylindrical portion 16a of
Since the ball 14 is rollingly contacted with the inner peripheral cylindrical portion 16a, it is easy to obtain concentricity with the motor shaft 1 fitted in the sintered oil-impregnated metal 2 and stabilize the trajectory of the ball 14 with high accuracy. be able to.

As described above, according to this embodiment, the orbit of the balls interposed between the rotor and the stator is stable, the concentricity with the motor shaft is high, and the surface runout and the rotation unevenness can be prevented. The bearing structure of the brushless motor can be realized.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to the drawings.

In FIG. 7, 1 is a motor shaft, 2 is a sintered oil-impregnated metal, 4 is a rotor frame, and 5 is a spindle hub. The above is the same as the configuration of FIG. Figure 2
The configuration is different from the above configuration in that the movable wheel of the thrust bearing is attached to the rotor, and the balls make rolling contact with the movable wheel at two points.

The operation of the motor bearing device constructed as described above will be described below.

A plurality of balls 14 held by a retainer 17 at equal intervals between the rotor and the stator of the motor.
A thrust bearing that receives a thrust load is provided with the fixed ring 16 rollingly contacting the ball at one point on the surface of the thrust bearing facing the ball 14 on the stator side.

The sintered oil-impregnated metal 2 is press-fitted into the bearing housing 3 mounted and fixed to the printed circuit board 7, the radial load of the motor is received by the sintered oil-impregnated metal 2, and the motor shaft 1 is rotatably supported. There is.

The outer peripheral portion of the movable wheel 15 is bent in the axial direction to provide a cylindrical portion 15a.
4 and the outer peripheral cylindrical portion 15a and the ball 14 are rolled at one point, so that the movable wheel 15 is rolled at the ball 14 at two points. Further, the inner peripheral portion 15b of the movable wheel 15 is fitted and attached to the spindle hub 5 of the rotor to center the inner peripheral portion 15b. Therefore, concentricity between the motor shaft 1 fitted inside the sintered oil-impregnated metal 2 and the outer peripheral cylindrical portion 15a of the movable wheel 15 can be easily obtained, and the trajectory of the ball can be stabilized with high accuracy.

As described above, according to the present embodiment, the orbit of the balls interposed between the rotor and the stator is stable, the concentricity with the motor shaft is high, and the thin axial type capable of preventing surface runout and uneven rotation. The bearing structure of the brushless motor can be realized.

The outer peripheral cylindrical portion of the movable wheel in this embodiment is bent at a right angle or less to the flat portion of the fixed wheel so that the opening angle between the flat portion and the cylindrical portion is 90 degrees or more to form a tapered outer peripheral cylindrical portion. A thrust bearing in which a ball is brought into rolling contact with a flat portion so as to receive a load in the radial direction may also be used.

(Embodiment 5) A fifth embodiment of the present invention will be described below with reference to the drawings.

In FIG. 8, 1 is a motor shaft, 2 is a sintered oil-impregnated metal, 4 is a rotor frame, and 5 is a spindle hub. The above is the same as the configuration of FIG. Figure 2
The difference from the configuration of is that the fixed ring of the thrust bearing is provided with a groove,
This thrust bearing device is used for axial type brushless motors other than radial type brushless motors by improving the load capacity of the bearings.

The operation of the motor bearing device constructed as described above will be described below.

The sintered oil-impregnated metal 2 is press-fitted into the bearing housing 3 mounted and fixed to the printed circuit board 7, and the load in the radial direction of the motor is received by the sintered oil-impregnated metal 2 to rotatably support the motor shaft 1. There is.

Between the rotor and the stator of the motor, a plurality of balls 14 held by a retainer 17 at equal intervals.
A thrust bearing that receives a thrust load is provided with the rotor 14 interposed therebetween, and a movable wheel 15 that makes rolling contact with the ball 14 at one point is provided on the surface of the thrust bearing that faces the ball 14 on the rotor side.

Further, a fixed ring 16 is provided on the surface of the thrust bearing facing the ball 14 of the stator, and the inner peripheral portion 16c of the fixed ring 16 is fitted into the bearing housing 3 to be attached, and the orbital position of the ball 14 is fixed. The wheel 16 is provided with a U groove or a V groove.

The contact pressure and the size of the contact surface in the case of the U groove are as shown in FIG. 9, and the basic dynamic load rating is about 8 as compared with the case of the flat surface when the shape factor is calculated by (Equation 2). It is suitable for a bearing device of a motor with a large thrust load. Further, the load capacity of the V groove is larger than that of the flat surface, and the life of the motor can be extended. Therefore, the bearing device of the axial type motor having a larger thrust load than the radial type can be used.

Since the inner peripheral portion 16c of the fixed ring 16 is fitted into the bearing housing 3, the raceway diameter of the groove formed in the fixed ring 16 is such that the motor shaft 1 fitted inside the sintered oil-impregnated metal 2 is inserted. Concentricity with and can be stably obtained with high accuracy.

Even if the groove is provided in the fixed ring 16, if the fixed ring 16 is not fitted to the centerable portion, the fixed ring moves due to impact and the surface run-out and uneven rotation are worsened. Further, even if the fixed ring 16 is centered and bonded to the stator, it is inclined and bonded due to uneven thickness of the adhesive material, and improvement in surface runout cannot be expected.

As described above, according to this embodiment, the trajectory of the balls interposed between the rotor and the stator is stable, the concentricity with the motor shaft is high, the surface runout and the rotation unevenness can be prevented, and the thrust load A large, thin brushless motor bearing structure can be realized.

(Embodiment 6) A sixth embodiment of the present invention will be described below with reference to the drawings.

In FIG. 10, 1 is a motor shaft, 2 is a sintered oil-impregnated metal, 3 is a bearing housing, 4 is a rotor frame, and 5 is a spindle hub. The above is the same as the configuration of FIG. The difference from the configuration of FIG. 8 is that a groove is provided in the movable wheel 15 of the thrust bearing.

The operation of the bearing device for a motor configured as described above will be described below.

The sintered oil-impregnated metal 2 is press-fitted into the bearing housing 3 fixed to the printed circuit board 7, and the load in the radial direction of the motor is received by the sintered oil-impregnated metal 2 to rotatably support the motor shaft 1. There is.

Between the rotor and the stator of the motor, a plurality of balls 14 held by a retainer 17 at equal intervals.
A thrust bearing that receives a thrust load is provided with the fixed ring 16 rollingly contacting the ball at one point on the surface of the thrust bearing facing the ball 14 on the stator side.

Further, a movable wheel 15 is provided on the surface of the thrust bearing facing the ball 14 of the stator, and the inner peripheral portion 15b of the movable wheel 15 is fitted to the spindle hub 5 of the rotor to center the movable wheel for mounting. Further, a U groove is provided in the movable wheel 15 at the orbital position of the ball 14.

When the groove is provided as in the sixth embodiment, the bearing has a large load capacity and can be used for a bearing device of a motor having a large thrust load.

As described above, according to the present embodiment, the trajectory of the balls interposed between the rotor and the stator is stable, the concentricity with the motor shaft is high, the surface runout and the rotation unevenness can be prevented, and the thrust load A large, thin brushless motor bearing structure can be realized.

(Embodiment 7) Hereinafter, a seventh embodiment of the present invention will be described with reference to the drawings.

In FIG. 11, 1 is a motor shaft, 2 is a sintered oil-impregnated metal, 3 is a bearing housing, 4 is a rotor frame, and 5 is a spindle hub. The above is the same as the configuration of FIG. The difference from the configuration of FIG. 8 is that grooves are provided in the fixed ring and the movable ring of the thrust bearing to improve the load capacity of the bearing.

The operation of the bearing device for a motor constructed as described above will be described below.

The sintered oil-impregnated metal 2 is press-fitted into the bearing housing 3 fixed to the printed circuit board 7, and the load in the radial direction of the motor is received by the sintered oil-impregnated metal 2 to rotatably support the motor shaft 1. There is.

Between the rotor and the stator of the motor, a plurality of balls 14 held by a retainer 17 at equal intervals.
A thrust bearing that receives a thrust load is provided to prevent surface runout of the rotor.

A fixed ring 16 is provided on the surface of the thrust bearing facing the ball 14 of the stator, and the inner peripheral portion 16 of the fixed ring 16 is provided.
c is fitted and mounted in the bearing housing 3, and further, a U groove or V groove is provided in the fixed ring 16 at the track position of the ball 14. Further, a movable wheel 15 is provided on the surface of the thrust bearing facing the ball 14 of the stator, and the inner peripheral portion 15b of the movable wheel 15 is provided.
Is fitted and attached to the spindle hub 5 of the rotor, and further, a U groove or V groove is provided in the movable wheel 15 at the orbital position of the ball 14.

When the grooves are provided on the two raceway surfaces, the load capacity is larger than that in the case of the flat surface, and the load capacity is larger than that in the case of one groove, so that the life of the motor can be extended.

As described above, according to the present embodiment, the bearing having grooves in the fixed wheel and the movable wheel has the inner peripheral portion of each wheel mounted coaxially with the motor shaft. The concentricity of the raceway diameter of the groove can be stably obtained, and a thin brushless motor bearing structure with a large thrust load without surface wobbling or uneven rotation can be realized.

[0090]

In the case of the embodiment, the height of the motor can be adjusted by inserting a washer between the fixed wheel and the printed circuit board or between the movable wheel and the spindle hub.

As described above, according to the present invention, the radial load of the motor is received by the sintered oil-impregnated metal, the motor shaft is rotatably supported via the sintered oil-impregnated metal, and the rotor-stator is interposed between the rotor and the stator. By providing a thrust bearing that receives a load in the thrust direction on the shaft, it is possible to provide an excellent bearing device for a radial type or axial type brushless motor that rotates stably and can satisfy performances such as shaft runout and jitter and is inexpensive. You can

[Brief description of drawings]

FIG. 1 is a sectional view of an FDD brushless motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a bearing device for a motor according to the first embodiment of the present invention.

FIG. 3 is an explanatory view showing the contact pressure and the size of the contact surface of the grooveless thrust bearing.

FIG. 4 is a diagram showing the relationship between thrust load and life of the thrust bearing according to the first embodiment of the present invention.

FIG. 5 is a sectional view of a bearing device for a motor according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a bearing device for a motor according to a third embodiment of the present invention.

FIG. 7 is a sectional view of a bearing device for a motor according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of a bearing device for a motor according to a fifth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the contact pressure and the size of the contact surface of the grooved thrust bearing.

FIG. 10 is a sectional view of a motor bearing device according to a sixth embodiment of the present invention.

FIG. 11 is a sectional view of a bearing device for a motor according to a seventh embodiment of the present invention.

FIG. 12 is a cross-sectional view of a brushless DC motor having a motor bearing device of Conventional Example 1.

FIG. 13 is a sectional view of a bearing device for a motor of Conventional Example 1.

FIG. 14 is a sectional view of a brushless DC motor having a motor bearing device of Conventional Example 2;

FIG. 15 is a sectional view of a bearing device for a motor of Conventional Example 2.

[Explanation of symbols]

 1 Motor shaft 2 Sintered oil-impregnated metal 3 Bearing housing 4 Rotor frame 5 Spindle hub 6 Stay housing 7 Printed circuit board 8 Stator core 9 Coil 10 Drive magnet 11 Drive pin 12 Hub magnet 13 FG magnet 14 Ball 15 Movable wheel 15a Cylinder of movable ring Part 15b Inner peripheral part of movable wheel 16 Fixed ring 16a Inner cylindrical part of fixed ring 16b Outer cylindrical part of fixed ring 16c Inner peripheral part of fixed ring 17 Retainer

Claims (7)

[Claims] 1. A fixing member having a stator core around which a coil is wound and a printed circuit board, a sintered oil-impregnated metal press-fitted into a bearing housing fixed to the printed circuit board of the fixing member, and a cylindrical drive. A magnet is fixed to the hanging portion of the rotor frame, and a thrust member is provided by interposing a ball between the rotating member of the motor and the fixed member, which rotates the rotor frame integrally with the motor shaft via the spindle hub. In a brushless motor provided with a thrust bearing for receiving a load, the thrust bearing has a movable ring on the rotating member side and a fixed ring on the fixed member side, and the movable wheel makes rolling contact with the ball at one point,
The bearing device for a radial type brushless motor, wherein the fixed ring makes rolling contact with the ball at one point. 2. The fixed ring is processed into a concave shape, and a sintered oil-impregnated metal is press-fitted into the inner peripheral cylindrical portion of the fixed ring, and the outer peripheral cylindrical portion of the fixed ring is fixed to the fixing member. Bearing device for radial type brushless motor. 3. A cylindrical portion is provided in the inner peripheral portion of the fixed ring in the axial direction, and a sintered oil-impregnated metal is press-fitted into the inner peripheral cylindrical portion, and the inner cylindrical portion and the ball are rollingly contacted at one point to fix the fixed portion. 2. The radial according to claim 1, wherein the flat portion of the ring is rollingly contacted with the ball at one point, and the fixed ring of the thrust bearing in which the outer peripheral portion of the fixed ring is fixed to the fixing member is rollingly contacted with the ball at two points. Type brushless motor bearing device. 4. A cylindrical portion is provided on the outer peripheral portion of the movable wheel in the axial direction, and the outer peripheral cylindrical portion and the ball make rolling contact at one point, and the flat portion of the movable wheel and the ball make rolling contact at one point. 2. The bearing device for a radial type brushless motor according to claim 1, wherein the movable wheel of the thrust bearing, which is mounted by fitting the inner peripheral portion of the movable wheel to the spindle hub, is rollingly contacted with the ball at two points. . 5. A radial type brushless motor, wherein a fixing member including a stator core around which a coil is wound and a printed circuit board, and a cylindrical drive magnet are fixed to a hanging portion of a rotor frame to form a motor shaft. A rotating member that rotates integrally, an axial type brushless motor, a fixed member that includes a plurality of coils and a printed circuit board, and a drive magnet fixed to the top surface side of the rotor frame to rotate integrally with the motor shaft. Between the rotary member, the sintered oil-impregnated metal press-fitted into the bearing housing fixed to the printed circuit board of the fixed member, the movable ring provided on the rotary member of the motor and the fixed ring provided on the fixed member, In a brushless motor provided with a thrust bearing that receives a thrust load with balls interposed, the thrust bearing The driving wheel makes rolling contact with the ball at one point, a groove is formed in the fixed ring of the thrust bearing to make rolling contact with the ball at two points, and the inner peripheral portion of the fixed ring is fitted into the bearing housing for mounting. Bearing device for brushless motors. 6. A brushless motor having a thrust bearing for receiving a thrust load with a ball interposed between a movable wheel provided on a rotating member of a motor and a fixed ring provided on a fixed member, wherein the thrust bearing is fixed. The ring is brought into rolling contact with the ball at one point, the movable wheel of the thrust bearing is provided with a groove to be brought into rolling contact with the ball at two points, and further, the inner peripheral portion of the movable wheel is fitted and attached to the rotary member. The bearing device for a brushless motor according to claim 5, wherein 7. A brushless motor having a thrust bearing receiving a thrust load with a ball interposed between a movable wheel provided on a rotating member of a motor and a fixed ring provided on a fixed member, wherein the thrust bearing is fixed. A groove is provided in the ring to make rolling contact with the ball at two points, and a groove is also provided in the movable ring of the thrust bearing to make rolling contact with the ball at two points, and the inner peripheral portion of the fixed ring is fitted to the bearing housing. The bearing device for a brushless motor according to claim 5, wherein the movable wheel has an inner peripheral portion fitted and attached to a rotating member.