JP2002010566A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor whose stator can be attached to a stationary member with high precision. SOLUTION: At least two members 21 with C-shaped cross-sections are provided between a stator 4 and a stationary member 1. The respective opening parts 21a of the C-shaped members 21 are arranged at least partially adjacent to each other in an axial direction while being shifted from each other circumferentially.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a spindle motor for rotating a magnetic disk such as a hard disk, an optical disk such as a CD-ROM, or a disk-shaped recording medium such as a magneto-optical disk.

[0002]

2. Description of the Related Art Magnetic disks such as hard disks and CDs
As a spindle motor for rotating and driving an optical disk such as a ROM or a disk-shaped recording medium such as a magneto-optical disk, there is one disclosed in, for example, JP-A-2000-83345. This conventional spindle motor
One end is fixed to the bracket, and the other end is fixed to a housing or the like of the recording medium driving device by means of screws or the like, and is separately fixed to the upper and lower parts of the shaft. A pair of ball bearings rotatably supporting a rotor hub on which a disk-shaped recording medium is mounted, a stator mounted on an outer peripheral surface of a shaft between the pair of ball bearings, and a position of the rotor hub radially opposed to the stator; And a rotor magnet disposed on the vehicle.

[0003] In this spindle motor, the rotor hub is rotated by the mutual magnetic action of the electromagnetic field generated by energizing the stator and the magnetic field of the rotor magnet. A large current needs to be supplied to the stator. However, when the current supplied to the stator increases, the electromagnetic vibration generated by energizing the stator also increases, and the electromagnetic vibration is transmitted to the housing of the recording medium driving device via the shaft and the bracket, and as a result, the recording is performed. The natural vibration frequency of the medium drive device and the frequency of the electromagnetic vibration transmitted from the spindle motor resonate, causing vibration and noise to increase.

[0004]

In the above-mentioned conventional spindle motor, in order to eliminate the problem of vibration and noise caused by such resonance, a motor is provided between the stator and the shaft.
A configuration is provided in which a cylindrical insulating member formed of a rubber-based material or the like having a vibration absorbing property is interposed to absorb electromagnetic vibrations before being transmitted to the shaft. Since it has a shape, in order to fit it to the shaft and fix it, the upper or lower outer peripheral surface of the shaft to which the ball bearing is fixed must pass through the inner peripheral surface of the insulating member. When the outer peripheral surface of the shaft is damaged, or when the insulating member is adhered and fixed to the outer peripheral surface of the shaft, the adhesive adheres to the fixing portion of the ball bearing. There is a problem that the rotation of the rotor hub may be deflected due to this.

Further, if the electrical conduction between the stator and the shaft is insulated by the insulating member, the static electricity generated in the stator cannot be discharged. When the charge exceeds a predetermined amount, a spark of static electricity is generated. In addition, there is a possibility that the dielectric breakdown of the stator core constituting the stator and the stator coil wound around the stator core may occur.

On the other hand, for example, there has been proposed a spindle motor having a configuration in which a C-shaped member formed of a member having conductivity and elasticity is interposed between a stator and a shaft. With this C-shaped member,
The electromagnetic vibrations generated in the stator are prevented from being transmitted to the shaft, and at the same time, the shaft can be mounted to the shaft in the radial direction. Adhesives and the like do not adhere to the shaft, preventing the deterioration of the mounting accuracy of the ball bearing to the shaft due to the mounting of the stator, etc., and also ensuring the electrical conduction between the stator and the shaft. Becomes However, since only one C-shaped member is interposed between the stator and the shaft, the circumferential dimension from the upper end in the axial direction to the lower end in the contact portion with the stator is compared by the opening of the C-shaped member. As a result, a large gap is generated, and the stator is mounted in a state of being slightly inclined or eccentric with respect to the axis of the shaft in the direction of the gap. Therefore, the gap between the stator and the rotor magnet is not fixed, and is in an unbalanced state, so that the above-described electromagnetic vibration increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spindle motor capable of accurately attaching a stator to a stationary member.

[0008]

According to the present invention, there is provided a spindle motor having a stationary member to which a stator is fixed, a rotating member having a driving magnet mounted opposite to the stator, and the rotating member having the stationary member. A spindle motor comprising a pair of ball bearings rotatably supported with respect to the stator, at least two members having a C-shaped cross section are interposed between the stator and the stationary member;
The character-shaped members are characterized in that at least a part of each opening is circumferentially different from the openings of the other C-shaped members, and are arranged adjacent to each other in the axial direction. (Claim 1).

This C-shaped member is formed of a member having both conductivity and elasticity, and an opening from the upper end to the lower end in the axial direction is formed in a part thereof. The attachment of the C-shaped member to the stationary member is performed from the radial direction of the stationary member through the opening due to the elastic deformation of the member. Is mounted in a state of being inclined or eccentric with respect to the rotation axis of the spindle motor, so that the gap dimension between the stator and the driving magnet is prevented from being unbalanced in the circumferential direction or the axial direction. In addition, there is no increase in the electromagnetic vibration due to the poor mounting of the stator.

In this case, assuming that the central angle of the opening of each C-shaped member is about 120 degrees with respect to the stationary member, each C-shaped member is circumferentially at least 60 degrees, preferably 90 degrees. By mounting differently, the stator can be accurately attached to the stationary member, and the gap between the stator and the driving magnet may be unbalanced in the circumferential direction or in the axial direction. Is prevented.

In the spindle motor according to the present invention, the stationary member includes a shaft, the stator is fixed to an outer peripheral surface of the shaft via the C-shaped member, and the pair of ball bearings includes: On the outer peripheral surface of the shaft, it is arranged separately at upper and lower portions in the axial direction of the stator (claim 2).

According to this structure, it is possible to prevent the gap between the stator and the driving magnet from being unbalanced in the circumferential direction or the axial direction, and at the same time, to prevent the outer circumferential surface of the shaft from being unbalanced. Damage due to the attachment of the stator, etc., and the adhesion of adhesives, etc. to the portion where the ball bearing is fixed are prevented, and the rotation of the rotating member may be deflected due to the poor mounting of the bearing. Is prevented from occurring.

Further, in the spindle motor according to the present invention, the stator is fixed to the stationary member via the two C-shaped members, and each opening of the two C-shaped members is It is characterized by being located 180 degrees opposite to the rotation axis of the rotation member (claim 3).

According to this configuration, by using two C-shaped members, it is possible to minimize the increase in the number of parts of the spindle motor, and at the same time, the axial line is provided at the contact portion between the stator and the stationary member. Since the generation of the gap in the entire direction is completely prevented, the gap between the stator and the driving magnet is more effectively prevented from being unbalanced in the circumferential direction or the axial direction.

In this case, the two C-shaped members are mounted so as to face each other from a direction perpendicular to the rotation axis of the spindle motor, so that the openings are positioned 180 degrees in the circumferential direction.

[0016]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a spindle motor according to an embodiment of the present invention, and FIG. 2 is a partially enlarged cross-sectional view showing a mounting portion of a stator of the spindle motor in FIG. FIG. 4 is a cross-sectional view showing a method of attaching a contact clip (C-shaped member) to a shaft, and FIG. 4 is a plan view schematically showing the contact clip.

The spindle motor according to the present invention comprises a shaft 1 which is a stationary member and a pair of ball bearings 2 and 3.
And a rotor 5 rotatably supported by the shaft 1 via the shaft 5. The stator 4 includes a stator core 4a and a stator coil 4b wound around the stator core 4a at a substantially central portion in the axial direction on the outer peripheral surface of the shaft 1.
Is attached. The structure of the mounting portion of the stator 4 to the shaft 1 and the mounting method will be described later in detail. The pair of ball bearings 2 and 3 have an inner ring fixed to the shaft 4 and an outer ring fixed to the inner peripheral surface of the rotor 5 by means such as bonding at upper and lower portions in the axial direction of the stator 4.

The rotor 5 has a rotor hub 5a on which a disk-shaped recording medium (not shown) such as a hard disk is placed, and is located radially inward of the rotor hub 5a. Yoke 5b made of a magnetic material and fixed so as to be opposed to each other with a gap in the radial direction.
And a bush 16 interposed between the yoke 5b and the outer ring of one of the ball bearings 3. The shaft 1 is located outside the bush 16 in the axial direction.
And a bush 16 cooperating with the flange 7 to form a labyrinth seal structure. Further, a magnetic fluid seal 12 is disposed outside the other ball bearing 2 in the axial direction. The labyrinth seal structure and the magnetic fluid seal 12 prevent dust and oil mist generated from the ball bearings 2 and 3 from leaking out of the spindle motor.

A pair of annular concave portions 1a and 1b each having a substantially semicircular cross section and an annular concave groove 1c having a substantially rectangular cross section are provided on a portion of the outer peripheral surface of the shaft 1 facing the inner peripheral surface of the stator 4. Are formed. Ring members (O-rings) 6, 6 made of an elastic member having heat resistance, such as rubber or resin, protrude radially outward from the outer peripheral surface of the shaft 1 in the annular concave portions 1a, 1b. Each is attached. Further, a pair of contact clips 21 and 21 formed of a heat-resistant resin or metal having conductivity and elasticity and having a C-shaped cross section as shown in FIG. Are mounted adjacent to each other in the axial direction so as to slightly protrude radially outward from the outer peripheral surface of the shaft 1.

As shown in FIG. 1 and FIG. 2, the stator 4 is attached to the shaft 1 by the ring members 6 and 6 and the contact clips 21 without directly contacting the outer peripheral surface of the shaft 1. That is, the stator coil 4b
Electromagnetic vibrations generated by energization of the shaft 1 are attenuated by these ring members 6 and 6 and the contact clips 21 and 21, so that direct transmission to the shaft 1 is prevented. Further, by forming the contact clips 21, 21 from a conductive member, electrical continuity between the stator 4 and the shaft 1 is ensured, and static electricity charged on the stator 4 is discharged through the shaft 1. .

Each of the contact clips 21 has an opening 21a having a central angle of about 120 degrees and a plurality of projections 22 provided radially on the outer peripheral surface. As shown in FIG. 3, the contact clips 21
It is mounted from a direction opposite to the axis of the shaft 1 (the axis of rotation of the spindle motor) by 180 degrees. By mounting each contact clip 21, 21 in the annular groove 1c such that the opening 21a is located at a position facing 180 degrees, the entire contact portion between the stator 4 and the contact clip 21, 21 in the axial direction is provided. Is not formed, the stator 4 can be mounted accurately without being inclined or eccentric with respect to the axis of the shaft 1. Therefore, the gap in the radial direction between the stator 4 and the rotor magnet 5c is unbalanced in the circumferential direction or the axial direction, thereby preventing an increase in electromagnetic vibration. Further, a plurality of projections 22 projecting radially from the outer peripheral surfaces of the contact clips 21, 21 are provided, and the projections 22 hold the stator 4.

The openings 21a of the contact clips 21, 21 are preferably mounted so as to be positioned 180 degrees opposite to each other with respect to the axis of the shaft 1. As described above, the openings 21a are provided. The central angle of 21a is about 120
Degree, the direction is more than 60 degrees in the circumferential direction, preferably 9 degrees.
By mounting the magnets so that they differ by 0 degrees or more, the gap between the stator 4 and the rotor magnet 5c is prevented from being unbalanced in the circumferential direction or the axial direction.

In the above description, one embodiment of the present invention has been described with reference only to the drawings, and the present invention is not limited thereto, and various modifications and changes can be made without departing from the gist of the present invention. It is.

For example, in the above description, a spindle motor in which a pair of contact clips 21 and 21 are mounted has been described. However, if the influence on the cost and the number of man-hours is small or the number is appropriately selected according to the characteristics. Is possible.

Further, in the above-described embodiment, the stator 4 is provided substantially at the center in the axial direction of the shaft 1 which is a stationary member.
The mounting structure of the stator according to the present invention has been described using an example of a fixed shaft type motor in which ball bearings 2 and 3 are arranged at upper and lower portions in the axial direction of the stator 4. The present invention is also applicable to a motor in which a pair of ball bearings are arranged in an upper part and a stator and a rotor magnet are arranged in a lower part, or a shaft rotation type motor in which a shaft rotates together with a rotor.

[0026]

According to the first aspect of the present invention, the gap between the stator and the driving magnet is prevented from being unbalanced in the circumferential direction or in the axial direction, and the stator is not properly mounted. Thus, a spindle motor with low vibration and low noise can be realized without increasing the electromagnetic vibration caused by the above.

According to the second aspect of the present invention, it is possible to prevent the gap between the stator and the driving magnet from being unbalanced in the circumferential direction or the axial direction. At the same time, damage to the portion where the ball bearing is fixed on the outer peripheral surface of the shaft is prevented, and adhesion of an adhesive or the like is prevented, and rotation of the rotating member is prevented from being deflected due to poor mounting of the bearing. Is done.

Further, according to the third aspect of the invention, it is possible to minimize the increase in the number of parts of the spindle motor, and at the same time, the gap between the stator and the driving magnet is reduced in the circumferential direction. Or an unbalanced state in the axial direction is more effectively prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a spindle motor according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a mounting portion of a stator in the spindle motor of FIG. 1 in an enlarged manner.

FIG. 3 is a cross-sectional view showing a method of attaching a contact clip (C-shaped member) to a shaft.

FIG. 4 is a plan view showing a schematic shape of a contact clip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft (static member) 2, 3 Ball bearing 4 Stator 5 Rotor (rotating member) 21 Contact clip (C-shaped member) 21a Opening

Claims (3)

[Claims] 1. A stationary member to which a stator is fixed, a rotating member having a driving magnet mounted opposite to the stator, and a pair of balls for rotatably supporting the rotating member with respect to the stationary member. A spindle motor including a bearing, wherein at least 2
Three C-shaped members are interposed, and the C-shaped member has at least a part of each opening different in a circumferential direction from the openings of the other C-shaped members,
A spindle motor which is arranged adjacent to each other in the axial direction. 2. The stationary member includes a shaft, the stator is fixed to an outer peripheral surface of the shaft via the C-shaped member, and the pair of ball bearings are disposed on the outer peripheral surface of the shaft. 2. The spindle motor according to claim 1, wherein the spindle motor is disposed separately at upper and lower portions in the axial direction of the stator. 3. The stator is fixed to the stationary member via the two C-shaped members, and the respective openings of the two C-shaped members are located at the rotation axis of the rotating member. 3. The spindle motor according to claim 1, wherein the spindle motor is positioned 180 degrees opposite to the spindle motor.