JP3142966B2 - Spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed shaft type spindle motor having a fixed shaft.

[0002]

2. Description of the Related Art A spindle motor generally comprises a stationary member mounted on a frame of a disk drive, a rotating member mounted with a recording medium and driven to rotate, and a bearing interposed between the stationary member and the rotating member. You. FIG. 2 is a sectional view of a conventional spindle motor. 101 is a bracket as a stationary member, and 102 is a fixed shaft erected at the center of the bracket 101. A stator 103 in which a coil 132 is wound around a stator core 131 is inserted into an intermediate portion of the fixed shaft 102. 104 is a hub member as a rotating member. The hub member 104 is a substantially bowl-shaped member made of, for example, aluminum, and has a disk mounting portion 141 protruding radially outward at an open end, and a recording disk (not shown) is mounted on the disk mounting portion 141. And stacked on the outer peripheral surface of the cylindrical portion 142. A first bush 105 made of a magnetic material such as stainless steel is mounted on an inner peripheral portion of the hub member 104. First
A rotor magnet 106 is provided on the inner peripheral surface of the bush 105 so as to face the stator 103. The closed end 151 of the first bush 105 is mounted on the fixed shaft 102 via the first bearing 171. Also, the first bush 10
5 has an annular second bush 10 on the inner peripheral surface 152 on the open end side.
8 is inserted, and the central portion 181 is mounted on the fixed shaft 102 via the second bearing 172. The lower end surface of the second bush 108 has a projection 182 projecting in the axial direction.
The bracket 101 facing the second bush 108 includes
Recess 111 corresponding to protrusion 182 of second bush 108
Is provided, a narrow space is formed between the protrusion 182 and the recess 111, and a labyrinth structure is formed such that impurities such as a lubricant of the second bearing 172 and an adhesive inside the motor do not easily scatter outside the motor. I have.

When manufacturing such a spindle motor, a rotating member and a stationary member are assembled as a general member. First, the hub member 10 is assembled as an assembly of the rotating member.
The cylindrical part 142 of No. 4 is fixed by means such as a chuck,
A first bush 105 on which a rotor magnet 106 is mounted in advance is fixed to the inner peripheral surface by shrink fitting. At this time, a positioning jig is applied from the open end so that the first bush 105 can be fixed to a predetermined position with respect to the hub member 104. Then, the outer ring of the first bearing 171 is bonded to the closed end 151 of the first bush 105 to form a rotating assembly member. On the other hand, in assembling the stationary member, first, the stator 103 is fixed to a predetermined position of the fixed shaft 102.
Next, the inner peripheral surface 181 of the second bush 108 is
72, and the inner ring of the second bearing 172 is fixed to the fixed shaft 1
02 to form a stationary assembly member. Then, the outer peripheral surface of the hub member 104 is chucked, the end surfaces 153 and 183 of the first bush 105 and the second bush 108 are aligned using a positioning jig, and the stationary assembly member and the rotary assembly member are joined.

[0004]

However, in the spindle motor having the above structure, the hub member 104 is not provided.
Inner peripheral surface 143 and outer peripheral surface 154 of first bush 105,
Alternatively, if the length of the adhesive surface between the inner peripheral surface 152 of the first bush 105 and the outer peripheral surface 184 of the second bush 108 is shortened in the axial direction, it is difficult for the axial direction of the hub member 104 to coincide with the axial direction of the first bush 105. At the time of mounting, the first bush 105 may be mounted to be inclined to the inner peripheral surface 143 of the cylindrical portion of the hub member 104, or the second bush 108 may be eccentrically fixed to the first bush 105. If the hub member 104 and the first bush 105 are eccentrically fixed, the distance between the rotor magnet 106 and the stator 103 becomes uneven, which tends to cause vibration and noise during rotation. If the first bush 105 and the hub member 104 are eccentric, the positioning of the second bush 108 can be adjusted by the hub member 1.
It becomes inaccurate for the fixed shaft 04 and the fixed shaft 102. Also,
If the second bush 108 is eccentrically mounted on the fixed shaft 102, the labyrinth space formed between the second bush 108 and the bracket 101 becomes uneven, and the labyrinth widths at the inner peripheral portion and the outer peripheral portion are different. If the width of the labyrinth space is different, a drift is generated in the air staying in the space, so that the so-called "Hump effect" occurs in which the air inside the motor is easily sucked.
As described above, the coaxiality in mounting each member is an important requirement for the performance of the motor.

[0005] By the way, when the length of the adhesive surface in the axial direction is short, it is difficult to obtain the coaxiality when the one member is fixed and the other member is pushed in using a positioning jig. This is because even if each member is eccentric at the time of insertion, it cannot be corrected by the positioning jig.

The present invention has been made in view of the above-described circumstances, and its main purpose is to provide a hub member 104 and a first bush 10.
5, and a spindle motor that does not use a positioning jig for mounting the first bush 105 and the second bush 108, and that can be assembled with the axes of the members being aligned.

[0007]

Means for Solving the Problems In order to achieve the above object, according to the present invention, a bracket, a fixed shaft mounted on the bracket, a stator inserted into the fixed shaft, and a A rotatable hub member, a pair of bearing members interposed between the fixed shaft and the hub member, an annular first bush made of a magnetic material disposed on an inner peripheral surface of the hub member, A rotor magnet mounted on the inner peripheral surface of one bush so as to face the stator;
And a second bushing mounted an annular between the bush, the first blanking protrudes radially inward on an inner peripheral surface of the hub member
A step facing the one end of the shoe , and the step
Partially annular projection projecting in the axial direction is formed, it abuts the end of the first bushing annular projection of the stepped portion in the axial direction,
The outer periphery of the second bushing includes a flange portion protruding radially outward, in contact with the axially the flange portion other end of the first bushing.

Further, the spindle motor of the present invention described above
The annular projection of the step of the hub member, the first bush, and the flange of the second bush are provided on the same line in the axial direction.
Is desirable .

[0009]

According to the spindle motor described above, the step of the hub member and the flange of the second bush are positioned, and one end of the first bush is inserted until it comes into contact with the step of the hub member. If the flange is brought into contact with and fixed to the other end of the first bush, the positional relationship between the hub member and the first bush can be secured without using a positioning jig. In addition, since the axial center is defined by the contact between the inner peripheral surface of the hub member and the outer peripheral surface of the first bush and the contact of the step, the accuracy is more accurate than when a positioning jig is used. Further, the step of the hub member and the first
Since the bush and the flange of the second bush are arranged on the same line in the axial direction, when the flange of the second bush is brought into contact with the first bush, the bush and the step of the hub member are connected via the first bush. And the inclination of the first bush is corrected.

[0010]

1 is a sectional view of a spindle motor according to the present invention. 4 is a hub member as a rotating member, 1 is a bracket as a stationary member, and 2 is a fixed shaft. 71, 7
Reference numeral 2 denotes a first bearing and a second bearing which are interposed between the stationary member and the rotating member and support the hub member 4 so as to be rotatable relative to the bracket 1 and the fixed shaft 2.

The bracket 1 has a spindle motor mounted on a frame (not shown) of a disk drive. The fixed shaft 2 is provided upright at the center of the bracket 1, and a stator 3 is mounted at an intermediate portion. The stator 3 is formed by winding a coil 32 around a stator core 31 in which magnetic steel sheets are laminated,
By applying a current to the coil 32, the stator core 3
The magnetic flux is converged on the first tooth (not shown).

The hub member 4 is a substantially bowl-shaped member made of, for example, aluminum and has a cylindrical portion 42 on which a magnetic disk (not shown) is mounted on a side surface and a closed end portion (upper end portion in FIG. 1). The clamp holding portion 43 located at the position, and the disk mounting portion 41 located at the open end (the lower end in FIG. 1).
Consists of The disk mounting portion 41 has a flange shape that is expanded radially outward from the outer diameter of the cylindrical portion 42, and a recording disk (not shown) is mounted thereon. Disk mounting part 4
A plurality of magnetic disks are stacked on the outer peripheral wall of the cylindrical portion 42 via a ring-shaped spacer on the upper surface of the recording disk mounted on the disk 1. The stacked magnetic disks are pressed and fixed from above by a clamp member attached to the clamp holder 43. Clamp holding part 43 of cylindrical part 42
A stepped portion 44 whose diameter is reduced radially inward is provided on the inner circumference. An annular protrusion 44 a is provided on the outer peripheral portion of the radial end surface of the step portion 44. The radial end surface of the annular projection 44a is accurately surface-machined perpendicularly to the axial direction of the cylindrical portion 42. An opening 4 is provided in the inner diameter portion of the clamp holding portion 43.
5 are provided, and the fixed shaft 2 passes through the center.
A magnetic fluid seal 90 is provided between the fixed shaft 2 and the inner peripheral surface 43 a of the clamp holder 43.

Reference numeral 5 denotes a first bush. First bush 5
Is formed of a magnetic material such as stainless steel, for example, and has a substantially bowl shape like the hub member 4. The first bush 5 includes a cylindrical portion 51 located at an open end and a bearing holding portion 52 located at a closed end. The outer peripheral surface of the cylindrical portion 51 is fixed to the inner peripheral surface of the hub member cylindrical portion 42 by shrink fitting. The upper end surface 51a and the lower end surface 51b of the first bush cylindrical portion 51 are accurately surface-machined perpendicularly to the axial direction of the first bush cylindrical portion 51, and the upper end surface 51a abuts on the annular protrusion 44a of the hub member 4. ing. First bush 5
The cylindrical portion 51 abuts against the annular projection 44a, not the entire circumference of the radial end face of the step portion 44, to relieve distortion due to thermal expansion due to the different materials of the hub member 4 and the first bush. That's why. . The outer race of the first bearing 71 is adhered to the inner peripheral surface 52 a of the bearing holder 52, and the inner race of the first bearing 71 is adhered to the fixed shaft 2. A cylindrical rotor magnet 6 is bonded to the inner peripheral surface of the first bush cylindrical portion 51 so as to face the stator 3. The rotating member rotates relatively to the stationary member due to the electromagnetic interaction between the rotor magnet 6 and the stator 3.

Reference numeral 8 denotes a second bush. Second bush 8
Is an annular member, and a first bushing cylindrical portion 51
A notch 81 having the same diameter as the inside diameter is provided over the entire circumference. The side surface 81a and the end surface 81b of the notch 81 are precisely machined in the vertical and horizontal directions, and the inner peripheral surface and the lower end 51b of the cylindrical portion of the first bush 5 are mounted. Second
The bush inner peripheral surface 82 is adhered to the outer ring of the second bearing 72, and has a lower end portion provided with an annular projection 83 projecting in the axial direction. On the other hand, a recess 11 corresponding to the annular projection 83 is provided on a surface of the bracket 1 facing the annular projection 83 of the second bush 8, and a narrow space is formed between the annular projection 83 and the recess 11. Thus, a labyrinth structure is formed in which impurities such as the lubricant of the second bearing 72 and the adhesive inside the motor do not easily scatter outside the motor.

When the spindle motor of this embodiment is manufactured, the cylindrical portion 42 of the hub member 4 is fixed by means such as a chuck, and the rotor magnet 6 is fixed to the inner peripheral surface thereof.
Is inserted until the upper end surface 51a of the cylindrical portion comes into contact with the radial end surface 44a of the step portion of the hub member 4,
It is fixed by shrink fitting. Further, the notch 81 of the second bush 8 is connected to the inner peripheral surface and the lower end surface 51 b of the cylindrical portion of the first bush 5.
And press-fit.

Although the embodiment of the spindle motor according to the present invention has been described above, the present invention is not limited to such an embodiment, and various modifications and alterations can be made without departing from the scope of the present invention. is there.

[0017]

According to the spindle motor of the present invention,
The step of the hub member and the notch of the second bush are positioned, and the upper end surface of the cylindrical portion of the first bush can be inserted until it comes into contact with the step radial end surface of the hub member. Can be brought into contact with the lower end of the hub, so that there is no need to use a positioning jig, and the axial center is defined by the contact between the inner peripheral surface of the hub member and the outer peripheral surface of the first bush and the step. Therefore, it is more accurate than when a positioning jig is used. Furthermore, since the step of the hub member and the notch of the first bush and the second bush are arranged on the same line in the axial direction, when the notch of the second bush is brought into contact with the first bush, It acts on the step of the hub member via the bush, and the inclination of the first bush is corrected, so that it is easier to manufacture than a conventional spindle motor, and a highly accurate spindle motor can be provided.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a spindle motor showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bracket 2 Fixed shaft 3 Stator 4 Hub member 5 1st bush 8 2nd bush 71 1st bearing 72 2nd bearing

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 5/10 H02K 5/173 H02K 15/16 H02K 29/00

Claims (2)

(57) [Claims] 1. A bracket, a fixed shaft mounted on the bracket, a stator inserted in the fixed shaft, a hub member rotatable relative to the fixed shaft, and a fixed shaft. A pair of bearing members interposed between the hub member,
An annular first bush made of a magnetic material disposed on an inner peripheral surface of the hub member, a rotor magnet mounted on the inner peripheral surface of the first bush so as to face the stator, and one bearing member A second bush mounted between the first bush and the first bush, wherein the hub member projects radially inward from an inner peripheral surface of the hub member .
A step facing the one end of the shoe , and the step
An annular projection protruding in the axial direction is formed in a part of the first projection .
One end of the bush is axially in contact with the annular projection of the step, and the outer periphery of the second bush is provided with a flange protruding radially outward, the flange being the other of the first bush. Axis at end
A spindle motor in contact with a direction . Wherein an annular protrusion of the step portion projecting radially inward on the inner periphery of said hub member, and the first bush, the second
2. The spindle motor according to claim 1, wherein the outer peripheral portion of the bush and the flange portion projecting outward in the radial direction are provided on the same line in the axial direction.