KR20060086612A - Spindle motor of hard disk drive comprising thrust bearing typed tube - Google Patents

Abstract

Spindle motor for the hard disk drive of the present invention is characterized by the shape of the thrust bearing coupled to the lower end of the shaft of the rotating body to support the shaft in the axial direction, thereby improving the coupling structure with the shaft design of the hydrodynamic bearing motor A spindle motor for a hard disk drive, which makes it easy to match the verticality between the shaft and the thrust bearing, which is an important factor in the present invention.

Accordingly, the present invention according to the present invention, the base is coupled to the inner side of the base and the groove is formed in a predetermined position grooves for inducing fluid dynamic pressure, the stator core is coupled to the upper portion of the base, is inserted into the inner diameter of the sleeve rotatable In the spindle motor for a hard disk drive comprising a shaft coupled to the lower end and the thrust bearing is coupled to the lower portion and the shaft is integrally coupled to the central portion and the magnet is attached to the position facing the stator core, The upper part of the thrust bearing has a predetermined height in a vertical direction, and is formed in a part of a protruding tube shape, and the outer diameter of the lower end of the shaft is inserted into the inner part of the protruding upper part, characterized in that the structure is combined.

Hard disk, spindle motor

Description

Spindle motor for hard disk drive with thrust bearing tube shape {SPINDLE MOTOR OF HARD DISK DRIVE COMPRISING THRUST BEARING TYPED TUBE}

1 is a view showing the external structure of a conventional hard disk drive.

2 is a view showing the internal structure of a conventional spindle motor to which a hydrodynamic bearing is applied.

3 is a view showing the internal structure of the spindle motor according to the present invention.

4 is a view for explaining a bearing portion of the spindle motor according to the present invention.

5 is a view showing a coupling state of the shaft and the thrust bearing according to the present invention.

Figure 6 is a view for comparing a conventional shaft coupled thrust bearing according to the present invention.

*** Brief description of the main symbols in the drawings ***

310: base 320: sleeve

330: stator core 340: shaft

350: hub 360: magnet

370a: Thrust bearing 370b: Thrust cover plate

380 groove 390 oil gap

392: Journal bearing part 394: Thrust bearing part

The present invention relates to a spindle motor for a hard disk drive, which is characterized by the shape of a thrust bearing and has improved coupling structure with the shaft, thereby improving the vertical control of the shaft, which is an important factor in the design of a hydrodynamic bearing motor.

In general, a hard disk drive refers to an auxiliary memory device that stores and reads data while rotating a magnetic aluminum plated aluminum substrate. However, a hard disk drive cannot be used interchangeably with other devices as needed. Because of its size, it is widely used in small computers.

In particular, small hard disk drives are widely used in personal computers because they are suitable for use in personal computers. The capacity of the hard disk drive used in such a personal computer is 1GB level in the mid-1990s, and 16GB level is common in the late 1990s. Globally, storage capacity is growing at 60% per year, with prices falling 12% per quarter.

Normally, the hard disk drive has a platter superimposed like a record plate and a concentric circle called a track is drawn thereon to record data electronically in the concentric circle. The hard disk drive 100 is briefly illustrated in FIG. It consists of a platter 200, a spindle motor 300, a head 400, a head arm 500 and a stepping motor 600.

The platter 200 is a thin coating of a magnetic material on a magnetic disk and due to the limitation of the capacity that can be recorded on one sheet, the high capacity hard disk drive 100 uses a plurality of platters 200 and its size and The size of the hard disk drive 100 is determined according to the number.

The spindle motor 300 rotates at a constant speed (for example, about 3600 times per minute (3600 rpm), 5400 times (5400 rpm), 7200 qjs (7200 rpm) when power is turned on as a motor for rotating the platter 200. One or more platters 200 are connected to each other on the spindle shaft to rotate simultaneously. In order to read / write reliable data, it is important to control the accurate rotation rate of the spindle motor 300.

The head 400 moves horizontally above and below the rotating platter 200 and reads and writes data to the platter 200, and the head arm 500 moves the arm 400 to move the head 400. As a command of the control circuit, the position of the head 400 is adjusted.

Finally, the stepping motor 600 is a driving force for moving the head 400 to the position of the platter 200, the performance of the motor is good or bad, according to the access time (: hard disk drive to place the data into the memory or Total time spent for transmission) is determined.

In particular, the spindle motor which is the field to which the present invention is applied belongs to a BLDC motor (Brushless-DC Motor) and transmits a rotational force to the center of the platter which is the disc of the disk to rotate the disk. In addition to motors for hard disk drives, laser beam scanner motors for laser printers, motors for floppy disk drives (FDD), and motors for optical disk drives such as compact disks (CD) or digital versatile disks (DVD) Widely used.

In recent years, in a device requiring high capacity and high speed driving force such as the hard disk drive, in order to minimize noise and non-repetitive run out (NRRO), a fluid having a lower driving load (or driving friction) than a conventional ball bearing type is required. The trend is to use spindle motors with dynamic bearings.

Here, the hydrodynamic bearing is basically a thin oil film formed between the rotating body and the fixed body to support the rotating body by the pressure generated during rotation, so that the friction load is reduced because the rotating body and the fixed body do not contact each other. Therefore, the fluid dynamic bearing spindle motor (Fluid Dynamic Bearing Spindle Motor) is applied to maintain the shaft of the motor that rotates the disk only lubricating oil (: pressure to return to the center of hydraulic pressure pushed by the centrifugal force of the rotating shaft) This is distinguished from the ball bearing spindle motor which supports the shaft with steel balls.

In addition, in the case of the spindle motor to which the ball bearing is applied, noise and vibration (NRRO: Non Repeatable Run Out) are generated due to friction between the ball bearing and the shaft, and in particular, the vibration acts as an obstacle to increasing the track density of the hard disk. However, in contrast, the hydrodynamic bearing has no metallic friction based on the centrifugal force, and as the rotation speed increases, a sense of stability increases, and therefore, the hydrodynamic bearing is preferentially employed in a hard disk drive due to its low noise and vibration characteristics.

As such, the internal structure of the conventional spindle motor to which the hydrodynamic bearing is applied includes a base 301, a sleeve 302, a stator core 303, a shaft 304, a hub 305 and the attached structure as shown in FIG. 2. It consists of a magnet 306.

The spindle motor 300 is a sleeve 302 is vertically coupled to the inside of the base 301 forming the appearance and the stator core 303 is wound on the upper side of the base 301 is mounted a coil and the sleeve The shaft 304 is rotatably inserted through the inner center of 302.

A disc-shaped thrust bearing 307a is rotatably coupled to the lower end of the shaft 304 and the lower end thereof is shielded from the outside by the thrust cover plate 307b, and the shaft 304 The upper end of the) is coupled to the hub hub 305 is open downward downward.

In addition, a magnet 306 is attached to a position facing the stator core 303 inside the end portion of the hub 305, and between the outer circumferential surface of the shaft 304 and the inner circumferential surface of the sleeve 302 and the thrust bearing 307a. An oil gap 309 is formed in the oil gap 309 so as to fill a fluid such as lubricating oil or grease.

Accordingly, the hydrodynamic bearing spindle motor having the above structure has a hub 305 and a shaft 304 coupled thereto by an electromagnetic repulsive force acting between the stator core 303 and the magnet 306 when an external power source is applied. ) Rotates.

In addition, a plurality of grooves 308 are formed on the inner circumferential surface of the sleeve 302 in a comb pattern (Herringbone) or spiral pattern (Sprial) form is filled in the oil gap 309 when the shaft 304 is rotated The oil moves toward the center of the groove 308 by the pressure gradient to generate fluid dynamic pressure to support the sleeve 302 in the radial direction of the shaft 304.

In addition, the thrust bearing 307a coupled to the lower end of the shaft 304 supports the shaft 304 in the axial direction. The thrust bearing 307a has a disc shape which is conventionally thin and press-fits to the shaft 304 to fix the shaft. .

However, when considering that the coupling should be made at a right angle with the shaft 304 at the time of coupling, it is not easy to form the right angle because the thickness thereof is thin, and it press-fits the thrust bearing 307a to press the shaft 304 exactly vertically. Since the strength is increased, the shape of the thrust bearing 307a may be deformed at this time.

In addition, the thrust bearing 307a supporting the shaft 304 in the axial direction is an important element in the design of the hydrodynamic bearing spindle motor. It is expected that the method can be combined at right angles to.

Accordingly, the present invention has been devised to solve the problems described above, and the vertical angle management so that the thrust bearing supporting the shaft in the axial direction (or vertical direction) when the shaft rotates to form a right angle when combined with the shaft. In order to improve the efficiency of the work, the thrust bearing has a predetermined height, the upper part of which consists of a tube shape protruding and the outer diameter of the lower end of the shaft is inserted into the inner diameter of the protruding upper shaft motor for a hard disk The purpose is to provide.

And, when the height of the protruding upper portion of the thrust bearing is coupled when coupled to the lower end of the shaft is at least 20% of the total length of the shaft to provide a spindle motor for a hard disk to form a sufficient coupling length when combined with the shaft There is another purpose.

In order to achieve the above technical problem, the present invention provides a base, a sleeve which is coupled to the inside of the base and grooves inducing fluid dynamic pressure is formed at a predetermined position, is coupled to the upper part of the base, and the coil is wound on the stator. A core, a shaft inserted into the inner diameter of the sleeve to be rotatably coupled, and a shaft to which a thrust bearing is coupled to a lower end thereof, and a hub attached to a position facing the stator core while the shaft is integrally coupled to the central portion. In a spindle motor for a hard disk drive,

The thrust bearing has a predetermined height in a vertical direction, and is formed in a part of a protruding tube shape, and the outer diameter of the lower end of the shaft is inserted into the protruding upper portion, characterized in that the structure is combined.

And, when the thrust bearing is coupled to the lower end of the shaft is preferably characterized in that the height of the protruding upper portion that is coupled is at least 20% of the total length of the shaft.

Hereinafter, a preferred embodiment of a spindle motor for a hard disk according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a view showing the internal structure of the spindle motor according to the invention, Figure 4 is a view for explaining the bearing portion of the spindle motor according to the invention, Figure 5 is a coupling state of the shaft and thrust bearing according to the invention 6 is a view for comparing a thrust bearing coupled shaft according to the present invention with the prior art.

As shown in FIG. 3, the internal structure of the spindle motor according to the present invention includes a hub 350 having a base 310, a sleeve 320, a shaft 340, a stator core 330, and a magnet 360. The structure is the same as before.

That is, the inside of the base 310, which is a fixing member, is fixed to the cylindrical sleeve 320 of which the upper and lower sides are opened, and the shaft 340 is rotatably mounted to the inner diameter of the sleeve 320 and the shaft 340. An oil gap 390 is formed between the outer diameter surface of the bottom surface) and the inner diameter surface of the sleeve 320. The fluid dynamic pressure is generated by the fluid filled in the oil gap 390. The fluid dynamic bearing, such as the application of the present invention, to which the fluid dynamic pressure is applied, inserts a fluid lubricant between two surfaces in relative motion to prevent friction or wear. The pressure is generated and lubricated according to the shape of the surface (aka groove) without the pressure applied from the outside, and is distinguished from the hydrostatic bearing in which the fluid between the two surfaces is lubricated by the pressure from the outside.

In addition, since the outer diameter increases by the combined thrust bearing 370a coupled to the lower end of the shaft 340, the inner diameter of the sleeve 320 is coupled to the elongated shaft 340. It is formed as large as the outer diameter of).

In addition, the upper one side of the shaft 340 is fixed to the hub 350, the stator core 330 and the magnet (330) at positions facing each other on the outside of the base 310 and the inside of the hub 350, respectively ( 360) is attached.

Here, the stator core 330 generates magnetic flux as a magnetic field is formed when current flows. The magnet 360 mounted at a position opposite to the magnet 360 repeatedly magnetizes the N pole and the S pole to form an electrode corresponding to the variable electrode generated in the stator core 330.

Therefore, the stator core 330 and the magnet 360 are generated by the repulsive force by the electromagnetic force due to the linkage of the magnetic flux, and thus the present invention is driven by the rotation of the hub 350 and the shaft 340 coupled thereto. .

In addition, as shown in Figure 4, the spindle motor according to the present invention, the journal bearing part (392) for supporting the shaft in the rotation radius direction during rotation and the thrust bearing is coupled to the lower end of the shaft and the outside and The shielding thrust cover plate is combined to be divided into a thrust bearing part (394) for supporting the shaft to prevent the shaft from rising upward when rotating. In addition, the journal bearing portion 392 and the thrust bearing portion 394 have a comb-toothed or spiral groove 380 for generating dynamic pressure.

On the other hand, the present invention has a major feature in improving the shape of the thrust bearing 370a and the resulting coupling structure in the thrust bearing portion 394.

Therefore, as shown in FIG. 5, the thrust bearing 370a according to the present invention has a predetermined height at the top in the vertical direction and has a partially protruding tube shape. The thrust bearing 370a and the shaft 340 are coupled to each other by inserting the outer diameter of the lower end of the shaft 340 into the inner diameter of the protruding upper portion. Here, in the coupling, the shaft 340 is press-fitted into the thrust bearing 370a (for example, by pressing three of them into a narrow hole or groove), but a method of bonding using an adhesive may be used.

Here, the coupling structure of the thrust bearing 370a and the shaft 340 according to the present invention will be compared with the related art with reference to FIG. 6.

As shown in FIG. 6A, the disk-shaped thrust bearing 370a is conventionally press-fitted and fixed to the lower end of the shaft 340 so that the press-in length L is very short, and thus the shaft 340 and The thrust bearing 370a is not easy to be combined to make the vertically accurate and the thrust bearing 370a is damaged due to the increase in the indentation strength.

On the contrary, as shown in FIG. 6B, the thrust bearing 370a according to the present invention induces a stable coupling with the shaft 340 because the indentation length L is secured by a predetermined height protruding in the vertical direction. In addition, since the shaft 340 is inserted into the protruding upper inner diameter of the thrust bearing 370a, vertical alignment is much easier than in the related art.

In addition, when the thrust bearing 370a is coupled to the lower end of the shaft 340, it is preferable that the height of the protruding upper part coupled to the thrust bearing 370a occupy at least 20% or more of the total length of the shaft 340. This is to ensure the optimum coupling length to ensure that the thrust bearing 370a and the shaft 340 are easily coupled to each other when the thrust bearing 370a and the shaft 340 are coupled to each other.

Meanwhile, an upper portion of the thrust bearing 370a coupled to the shaft 340 is spaced a predetermined distance from the sleeve 320, which is at least 0.4 mm to facilitate groove processing formed in the sleeve 320. It is good to form a space, more preferably 0.6 mm.

Although the present invention described above has been described in detail only with respect to the specific examples described, it will be apparent to those skilled in the art that various modifications and changes are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims. .

As described above, the present invention has a thrust bearing for supporting a shaft that rotates when the spindle motor for a hard disk drive is driven in the axial direction to prevent the shaft from rising upward during rotation, and has a tube shape in which the upper part protrudes. Since the outer diameter of the lower end of the shaft is inserted into the protruding inner diameter, the coupling is performed. Therefore, as compared with the conventional, the coupling length between the thrust bearing and the shaft is increased by the height of the protruding height, so that it is easy to match the verticality and there is an effect of preventing the thrust bearing due to the indentation strength during the coupling.                     

In addition, in the design of a hydrodynamic bearing spindle motor, the vertical rotation of the rotating body, that is, the shaft, is an important factor in the rotational movement. In view of this, the effect of the present invention is expected to be large.

Claims (2)

The base 301, the sleeve 302 is coupled to the inside of the base 301 and the groove for inducing fluid dynamic pressure is formed at each predetermined position, the stator core coupled to the upper portion of the base 301 and the coil is wound ( 303, the shaft 304 inserted into the inner diameter of the sleeve 302 and rotatably coupled to the lower end thereof, and the shaft 304 having the thrust bearing 307a coupled to the lower end thereof are integrally coupled to the central portion of the stator core 303. In the spindle motor for a hard disk drive having a structure comprising a hub 305 to which the magnet 306 is attached to a position facing the) The thrust bearing 370a has a predetermined height in the vertical direction and is formed in a part of a protruding tube shape, and has a structure in which an outer diameter of the lower end of the shaft 340 is inserted into an inner diameter of the protruding upper portion. Spindle motors for hard disk drives. The method of claim 1, wherein the thrust bearing (370a) is When coupled to the lower end of the shaft, the height of the protruding upper portion is coupled to the spindle motor for a hard disk drive, characterized in that at least 20% of the total length of the shaft.

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