JPH06113501A - Spindle motor - Google Patents

Abstract

PURPOSE:To allow assembling without requiring any positioning jig by a constitution wherein a first bush abuts at one end part thereof on the inner peripheral step of a hub member, a second bush abuts at the flange part thereof on one end part of the first bush, with the step part of the hub member being aligned axially with the flange parts of the first and second bushes. CONSTITUTION:A step part 44 is provided radially inward in the vicinity of the clamp holding part 42 on the inner peripheral part 42 of a hub member 4 and an annular protrusion 44 is provided at the outer peripheral part on the radial end face of the step part 44 being machined vertically to the axial direction of a cylindrical part 42 with high accuracy. Cylindrical section 51 of first bush has upper and lower end faces 51a, 51b machined vertically to the axial direction of the cylindrical section 51 with high accuracy wherein the upper end face 51a abuts on the annular protrusion 44a of the hub member 4. A notch 81 is made entirely in the outer (peripheral part of a second bush 8 with the side face 81a and the end face 81b thereof being machined highly accurately in vertical and horizontal directions, respectively, so that the inner peripheral face at the cylindrical section of the first bush 5 and the lower end part 51b are loaded, respectively, thereon.

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 is generally composed of a stationary member mounted on a frame of a disk drive device, a rotating member for mounting a recording medium for rotational driving, and a bearing interposed between the stationary member and the rotating member. It FIG. 2 is a sectional view of a conventional spindle motor. Reference numeral 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 and installed in an intermediate portion of the fixed shaft 102. A hub member 104 is a rotating member. The hub member 104 is a substantially bowl-shaped member formed of, for example, aluminum, and has a disc mounting portion 141 that projects outward in the radial direction at the open end, and the recording disc (not shown) is the disc mounting portion 141. And is 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 attached to 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 attached to the fixed shaft 102 via the first bearing 171. In addition, the first bush 10
5, the annular second bush 10 is provided on the inner peripheral surface 152 on the open end side.
8 is inserted and the central portion 181 is attached to the fixed shaft 102 via the second bearing 172. The lower end surface of the second bush 108 is provided with a protrusion 182 protruding in the axial direction, while
In the bracket 101 facing the second bush 108,
The recess 111 corresponding to the protrusion 182 of the second bush 108
Is provided, and a narrow space is provided between the protrusion 182 and the recess 111, and a labyrinth structure is formed so that impurities such as the lubricant of the second bearing 172 and the adhesive inside the motor are not easily scattered to the outside of the motor. There is.

When manufacturing such a spindle motor, a rotary member and a stationary member are assembled as a general member. First, the hub member 10 is used to assemble the rotating member.
The cylindrical portion 142 of 4 is fixed by means such as a chuck,
The first bush 105, to which the rotor magnet 106 is previously attached, is fixed to the inner peripheral surface by shrink fitting. At that time, a positioning jig is applied from the open end side so that the first bush 105 can be fixed to the hub member 104 at a predetermined position. Then, the outer ring of the first bearing 171 is bonded to the closed end 151 of the first bush 105 to form a rotary 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 attached to the second bearing 1
72 is bonded to the outer ring, and the inner ring of the second bearing 172 is fixed to the fixed shaft 1
It is mounted at a predetermined position 02 to form a stationary assembly member. Then, the outer peripheral surface of the hub member 104 is chucked, the end faces 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 rotating assembly member are joined together.

[0004]

However, in the spindle motor having the above structure, the hub member 104 is used.
Inner peripheral surface 143 and outer peripheral surface 154 of the 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 becomes shorter in the axial direction, it becomes difficult for the axial direction of the hub member 104 and the axial direction of the first bush 105 to coincide with each other. At the time of mounting, the first bush 105 may be mounted while being inclined with respect 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 to each other, the gap between the rotor magnet 106 and the stator 103 becomes nonuniform, which easily causes vibration and noise during rotation. Further, if the first bush 105 and the hub member 104 are eccentric, the positioning of the second bush 108 can also be performed by the hub member 1.
04 and the fixed shaft 102 are not accurate. Also,
If the second bush 108 is mounted eccentrically with respect to 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 differ. When the labyrinth spaces have different widths, a drift occurs in the air retained in the spaces, so that a so-called hoop action is generated, which makes it easier to suck the air inside the motor.
As described above, the coaxiality in mounting each member is an important requirement for the performance of the motor.

By the way, if the length of the bonding surface in the axial direction is short, it is difficult to obtain the coaxiality in the process of fixing one member and pushing the other member by using the positioning jig. Because the number is small, 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 facts, and its main purpose is the hub member 104 and the first bush 10.
5, and to provide a spindle motor in which a positioning jig is not used for mounting the first bush 105 and the second bush 108, and moreover, the shaft cores of the respective members can be assembled so as to match each other.

[0007]

In order to achieve the above object, according to the present invention, a bracket, a fixed shaft mounted on the bracket, a stator inserted in the fixed shaft, and a relative rotation with respect to the fixed shaft. A free 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 and disposed on the inner peripheral surface of the hub member, and a first bush. An inner peripheral surface of the hub member, the rotor magnet mounted on the inner peripheral surface of the rotor facing the stator, and the annular second bush mounted between the one bearing member and the first bush or the hub member. Is provided with a step portion projecting radially inward, one end of the first bush is in contact with the step portion, and a flange portion projecting radially outward is provided on the outer peripheral portion of the second bush, and the flange portion is the first 1 The bush or hub member is in contact with one end thereof.

Further, the step portion of the hub member, the first bush, and the flange portion of the second bush are provided on the same line in the axial direction.

[0009]

According to the spindle motor described above, the step portion of the hub member and the flange portion of the second bush are positioned, and one end portion of the first bush is inserted until it abuts on the step portion of the hub member. If the flange portion is brought into contact with and fixed to the other end portion of the first bush, the positional relationship between the hub member and the first bush can be secured without using a positioning jig. Moreover, since the axial centrality is defined by the contact between the stepped portion and the adhesion surface between the inner peripheral surface of the hub member and the outer peripheral surface of the first bush, it is more accurate than when a positioning jig is used. Further, the step portion of the hub member and the first
Since the flange portions of the bush and the second bush are arranged on the same line in the axial direction, when the flange portion of the second bush is brought into contact with the first bush, the flange portion of the hub member is inserted through the first bush. The inclination of the first bush is corrected.

[0010]

1 is a sectional view of a spindle motor according to the present invention. Reference numeral 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 erected at the center of the bracket 1, and the stator 3 is attached to the middle portion thereof. In the stator 3, a coil 32 is wound around a stator core 31 formed by laminating magnetic steel sheets,
By passing a current through the coil 32, the stator core 3
The magnetic flux is converged on the tooth portion 1 (not shown).

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

Reference numeral 5 is a first bush. First bush 5
Is made of a magnetic material such as stainless steel, and has a substantially bowl shape like the hub member 4. The first bush 5 includes a cylindrical portion 51 located at the open end and a bearing holding portion 52 located at the 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 precisely 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 is brought into contact with the annular protrusion 44a instead of the entire circumference of the radial end surface of the step portion 44 because the strain of thermal expansion due to the different materials of the hub member 4 and the first bush is released. This is because. . The outer ring of the first bearing 71 is bonded to the inner peripheral surface 52a of the bearing holding portion 52, and the inner ring of the first bearing 71 is bonded 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. Due to the electromagnetic interaction between the rotor magnet 6 and the stator 3, the rotating member rotates relative to the stationary member.

Reference numeral 8 is a second bush. Second bush 8
Is an annular member, and the first bush cylindrical portion 51 is provided on the outer peripheral portion.
A notch 81 having the same diameter as the inner diameter of is provided over the entire circumference. The side surface 81a and the end surface 81b of the notch 81 are accurately machined in the vertical direction and the horizontal direction, and the inner peripheral surface of the cylindrical portion and the lower end portion 51b 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 the lower end portion thereof is provided with an annular protrusion 83 protruding in the axial direction. On the other hand, a recess 11 corresponding to the annular protrusion 83 is provided on the surface of the second bush 8 of the bracket 1 facing the annular protrusion 83, and a narrow space is provided between the annular protrusion 83 and the recess 11. The labyrinth structure prevents impurities such as the lubricant of the second bearing 72 and the adhesive inside the motor from easily scattering outside the motor.

By the way, when the spindle motor of this embodiment is manufactured, the cylindrical portion 42 of the hub member 4 is fixed by means of a chuck or the like, and the rotor magnet 6 is attached to the inner peripheral surface thereof.
Insert the first bush 5 mounted with until the upper end surface 51a of the cylindrical portion comes into contact with the step radial end surface 44a of the hub member 4,
It is fixed by shrink fitting. Further, the notch 81 of the second bush 8 is formed on the inner peripheral surface of the cylindrical portion of the first bush 5 and the lower end surface 51b.
Abut and press fit.

Although one embodiment of the spindle motor according to the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and corrections 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 portion of the hub member and the notch of the second bush serve as positioning, and the upper end surface of the cylindrical portion of the first bush can be inserted until it abuts the radial end surface of the step portion of the hub member, and the notch of the second bush is the first bush. Since it can be brought into contact with the lower end portion of the shaft, it is not necessary to use a positioning jig, and the axialness is defined by the contact between the stepped portion and the bonding surface between the inner peripheral surface of the hub member and the outer peripheral surface of the first bush. Therefore, it is more accurate than when a positioning jig is used. Further, since the step portion 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, the first bush Since it acts on the step portion of the hub member through the bush and the inclination of the first bush is corrected, it is easier to manufacture than the conventional spindle motor, and a spindle motor with high accuracy can be provided.

[Brief description of 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]

 1 bracket 2 fixed shaft 3 stator 4 hub member 5 first bush 8 second bush 71 first bearing 72 second bearing

Claims (2)

[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 the fixed shaft. A pair of bearing members interposed between the hub member,
An annular first bush made of a magnetic material is disposed on the 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. And an annular second bush mounted between the first bush and the first bush, wherein the inner peripheral portion of the hub member is provided with a step portion projecting radially inward. One end portion of the second bush is in contact with the step portion, and a flange portion protruding outward in the radial direction is provided on the outer peripheral portion of the second bush, and the flange portion is in contact with one end portion of the first bush. Spindle motor characterized by. 2. The spindle motor according to claim 1, wherein the step portion radially inwardly protruding to the inner peripheral portion of the hub member, the first bush, and the outer peripheral portion of the second bush have diameters. The spindle motor according to claim 1, wherein the flange portion projecting outward in the direction is provided on the same line in the axial direction.