KR100660180B1 - Spindle motor for hdd improved on union construction of sleeve and shaft - Google Patents

Abstract

A spindle motor for an HDD(Hard Disc Drive) in which a combining structure of a sleeve and a shaft is improved is provided to prevent the separation of the shaft without using an existing thrust bearing, easily secure the perpendicularity of the shaft, and be easily assembled. A rotary part includes a hub(10) and a shaft(30). The hub(10) is formed as a downward opened cap shape, and a magnet(20) is installed at an internal side of the hub(10). One side of the shaft(30) is combined to the center of the hub(10). A fixing groove(300) partially caved at an internal side is formed in a certain position along an outer circumference surface of the shaft(30). A fixing part includes a sleeve(50), a base(60), a stator core(70), a cover plate(90), and a fixing pin(100). The sleeve(50) has an oil gap so that it is possible for the shaft(30) to be rotated. The sleeve(50) is combined with the shaft(30). A through hole(500), having a certain size, which penetrates an internal part of the sleeve(50) is formed in a position corresponding to the fixing groove(300) of the shaft(30). A radial direction dynamic pressure generation groove(81) for generating dynamic pressure at an internal side is formed in a certain position of the sleeve(50). The base(60) fixes the sleeve(50). The stator core(70) on which a coil is wound is combined to the base(60) to be faced with the magnet(20). A cover plate(90) closes one side of the sleeve(50). An axial direction dynamic pressure generation groove(82) is formed in an upper surface faced with a lower surface of the shaft(30) in the cover plate(90). The fixing pin(100) passes through the through hole(500) of the sleeve(50), and connects to the fixing groove(300) of the shaft(30) to have an oil gap.

Description

SPINDLE MOTOR FOR HDD IMPROVED ON UNION CONSTRUCTION OF SLEEVE AND SHAFT}

1 is a view for briefly explaining the structure of a typical hard disk drive.

Figure 2 is a view for briefly explaining the structure of a conventional spindle motor for a hard disk drive.

3 is a view for conceptually explaining the structure of a spindle motor for a hard disk according to the present invention.

4 is a view for explaining a shaft and a sleeve according to the present invention.

5 is a view for explaining a fixing pin and a cover plate according to the present invention.

6 is a view for explaining the generation of dynamic pressure according to the present invention.

*** Brief description of the reference numerals for the main parts of the drawings ***

1: platter 2: spindle motor

3: head 4: head arm

5: sppping motor

10: HUB 20: MAGNET

30: shaft 40: thrust bearing

50: SLEEVE 60: Base

70: stator core 80: groove (GROOVE)

90: cover plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for providing rotational force to a plurality of platters in a hard disk drive (HDD), and more particularly to a coupling form and structure of a shaft and a sleeve constituting the spindle motor.

In general, a hard disk drive refers to an auxiliary gear device that stores and reads data while rotating a disk-shaped aluminum plate coated with a magnetic material. 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 was basically 1GB in the mid-1990s, and 16GB in the late 1990s. Globally, storage capacity is growing at 60% per year, with prices falling 12% per quarter.

Usually, the hard disk drive has a platter shaped like a record plate, and a concentric circle called a track is drawn thereon to record data electronically in the concentric circle. As shown in FIG. (1) consists of a stacked hard disk, spindle motor (2), head (3), head arm (4) and stepping motor (5).

The platter (1) is a thin coating of magnetic magnetic material on a metal disc, and due to the limitation of the capacity that can be recorded on one sheet, a high capacity hard disk uses several platters (1), depending on the size and number of hard disks. The size of is determined.

The spindle motor 2 is a motor that rotates the platter 1 to rotate at a constant speed (for example, 3600 rpm, 5400 rpm, 7200 rpm) when the power is turned on, so that at least one platter 1 rotates simultaneously on the spindle shaft. It is. Controlling the exact rotation rate of the spindle motor 2 is of paramount importance for reliable reading and writing of data.

The head 3 then moves horizontally above and below the rotating platter 1 to read and write data to the platter 1. In addition, the head arm 4 is an arm that allows the head 3 to move and adjusts the position of the head 3 under the command of the controller chip.

Finally, the stepping motor 5 is a driving force for moving the head 3 to the position of the platter 1, and the performance of the motor is good or bad. Total time spent for transmission) is determined.

In particular, the spindle motor in the field to which the present invention is applied belongs to a brushless-DC motor and transmits a rotational force to the center of the platter which is the disc of the disk to rotate the platter. In addition to the hard disk drive, the main motor is widely used as a laser beam scanner motor for a laser printer, a motor for a floppy disk drive (FDD), and an optical disk drive motor such as a compact disk (CD) or a digital versatile disk (DVD). do.

In addition, recently, in a machine 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 with 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, a 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 the hydraulic pressure driven by the centrifugal force of the rotating shaft) It 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) occur 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 has a base 60, a sleeve 50, a coil wound stator core 70, a shaft 30, and a hub as shown in FIG. 10 and the magnet 20.

The spindle motor is fixed to the sleeve 50 is vertically coupled to the inside of the base 60 forming the abduction, and the stator core 70 is wound around the upper side of the base 60 is mounted and the sleeve 50 of the The shaft 30 is rotatably inserted through the inner center. And the lower end of the shaft 30 is coupled to the disk-shaped thrust bearing 40 rotatably coupled with the shaft 30 and its lower end is shielded from the outside by a cover plate, the upper end of the shaft 30 is internal The cap-shaped hub 10 opened downward is coupled. In addition, a magnet 20 is attached to a position facing the stator core 70 inside the end of the hub 10, and an oil gap between the outer circumferential surface of the shaft 30 and the thrust bearing 40 and the sleeve 50. This oil gap is filled with fluid such as lubricating oil or grease.

Therefore, the hydrodynamic bearing spindle motor having the above structure has a hub 10 and a shaft coupled thereto by an electromagnetic repulsive force acting between the stator core 70 and the magnet 20 in which the coil is wound when an external power source is applied. 30 rotates.

In addition, a plurality of grooves 80 are formed in a comb pattern (Herringbone) or spiral form on the inner circumferential surface of the sleeve 50, so that the oil filled in the oil gap in the pressure gradient is rotated when the shaft is rotated. As a result, fluid dynamic pressure is generated while moving toward the center of the groove 90 to support the shaft 30, thereby preventing the fluid filled in the oil gap from scattering.

However, as shown in FIG. 2, in the related art, the thrust bearing 40 coupled with the shaft 30 should be accurately matched with the verticality of the thrust bearing 40 and the shaft 30 at the time of manufacture of the product, and the thrust bearing Even when the 40 is coupled to the shaft 30, the vertical alignment with the cover plate 90 needs to be precisely adjusted once again, thereby causing a lot of difficulties in the manufacturing process.

In addition, the conventional spindle motor does not discharge a small amount of air particles present in the fluid inside the hydrodynamic bearing to the outside, the temperature rises due to the frictional heat generated by the friction of the hydrodynamic bearing, resulting in thermal expansion and oil This leakage causes a problem of shortening the life of each part of the hydrodynamic bearing with an increase in NRRO, which is fatal to driving characteristics.

The spindle motor for a hard disk drive with improved coupling structure of the sleeve and the shaft of the present invention was devised to overcome the problems of the conventional spindle motor as described above, and prevents the shaft from being separated without using the conventional thrust bearing. It is an object of the present invention to provide a spindle motor for a hard disk drive, which is easy to secure the verticality of the shaft and thus, the assembly of the product.

In addition, another object of the present invention is to provide a spindle motor for a hard disk drive that easily discharges air particles present in a fluid inside a fluid dynamic bearing to an outside to improve driving characteristics and prevent leakage of fluid inside the fluid dynamic bearing. have.

In order to achieve the above object, the spindle motor for a hard disk drive having improved coupling structure between the sleeve and the shaft of the present invention is a spindle motor for a hard disk drive using a hydrodynamic bearing. A shaft 30 having one side coupled to the center of the hub 10 having the hub 20 installed thereon, and having a fixing groove 300 recessed inward at a predetermined position along an outer circumferential surface thereof; A through-hole having a predetermined size penetrating the inside at a position corresponding to the fixing groove 300 of the shaft 30 with an oil gap so that the rotating part and the shaft 30 can rotate. A sleeve 50 which forms a ball 500 and a radial direction dynamic pressure generating groove 81 for generating dynamic pressure on an inner surface thereof is formed at a predetermined position; and a base 60 for fixing the sleeve 50. ); And a stator core 70 in which a coil coupled to the base 60 is wound so as to face the magnet 20; and one side of the sleeve 50 is closed, and the upper surface is in contact with the lower surface of the shaft 30. A cover plate 90 on which an axial dynamic pressure generating groove 82 is formed; And a fixing pin 100 penetrating the through-hole 500 of the sleeve 50 in a pin shape to be connected to the fixing groove 300 of the shaft 30 to have an oil gap. It is characterized by including.

In addition, one or more fixing pins 100 are provided, so that the through holes 500 and the fixing grooves 300 of the shaft 30 of the sleeve 50 correspond to the fixing pins 100, respectively. It is characterized by being formed.

Here, the fixing pin 100 discharges air particles from the oil gap between the sleeve 50 and the shaft 30 in a pipe shape having an empty inside, and an air discharge groove 510 for discharging them to the outside. Is formed at a predetermined position of the outer peripheral surface of the sleeve 50 is characterized in that it is connected to the fixing pin 100.

Hereinafter, a spindle motor for a hard disk drive having an improved coupling structure between the sleeve and the shaft of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view for conceptually explaining the structure of a spindle motor for a hard disk according to the present invention. As shown in FIG. 3, the spindle motor for a hard disk drive is largely divided into a rotating part and a fixing part.

First, the rotating part is formed of a hub 10 in which the magnet 20 is installed on the inner side in a cap shape opened downward and a shaft 30 having one side coupled to the center of the hub 10.

At this time, the shaft 30 is coupled to the center of the hub 10 is characterized in that the fixing groove 300 is formed with a portion recessed inward at a predetermined position along the outer peripheral surface.

On the other hand, the fixing portion has an oil gap so that the shaft 30 is rotatable, coupled to the shaft 30 and one side is closed by a cover plate 90, the radial for generating dynamic pressure on the inner surface A coil 50 coupled to the base 60 to face the sleeve 50 having the directional dynamic generating groove 81 formed at a predetermined position, the base 60 fixing the sleeve 50 and the magnet 20, A wound stator core 70 is formed.

Here, in the spindle motor according to the present invention, there is no thrust bearing used in the conventional spindle motor, and a groove 82 for axial dynamic pressure generation is formed in the cover plate 90, and the shaft 30 It is characterized in that the fixing pin 100 of a predetermined pin shape for preventing the separation is further configured.

In other words, the spindle motor for a hard disk drive according to the present invention is coupled to the magnet 20 to the inner surface of the cap-shaped hub 10 opened downward, the stator core 70 wound around the coil coupled to the base 60 The hub 10 is rotated by the electric repulsive force formed by the current and the voltage applied thereto. At this time, by using a hydrodynamic bearing as a bearing means for smooth and stable rotation of the hub 10, the friction and resistance of the object during the rotational movement, as well as the noise and vibrations significantly reduced.

At this time, the shaft 30, the sleeve 50, the cover plate 90 and the fixing pin 100 constituting the hydrodynamic bearing has a shape as shown.

That is, the cover plate 90 and the fixing pin 100 replaces the role of the conventional thrust bearing.

Conventional thrust bearings have a structure that is integrally formed with the shaft or coupled to the shaft in the process of producing the shaft, the thrust bearing stably holds the center of gravity when the shaft is rotated at high speed, and secures and supports the shaft It also plays a role. The cover plate 90 and the fixing pin 100 take the role of such a thrust bearing.

Therefore, in the present invention, due to the conventional thrust bearing, there is a feature that can solve the difficulty of precisely adjusting the vertical double when assembling in the product manufacturing process.

The shaft 30 which is coupled to one side of the hub 10 is inserted into and coupled to the inside of the sleeve 50 to form an oil gap, which is a space into which oil is injected.

Thus, by means of oil filled in the oil gap, the rotating shaft rotates together with the hub 10 in the sleeve 50 coupled to the base 60. At this time, grooves 81 and 82 for generating dynamic pressure in the radial and axial directions of the rotating shaft are formed on the inner circumferential surface of the sleeve 50 and the upper surface of the cover plate 90.

In the present invention, the grooves 81 and 82 have radial radial pressure generating grooves 81 formed on the inner circumferential surface of the sleeve 50, that is, the surface in contact with the shaft 30, and the cover plate 90 is formed. Axial direction dynamic pressure generating grooves 82 are formed on the upper surface, that is, the surface contacting the lower end of the shaft 30.

Here, the grooves 81 formed on the inner circumferential surface of the sleeve 50 are formed in the upper end and the lower end, respectively, because the fixing groove 500 is formed in the middle portion of the sleeve 50. Radial direction dynamic pressure generating grooves 81 are formed at the upper and lower ends, respectively, except for 500.

As described above, a radial direction dynamic pressure generating groove 81 is formed on the inner circumferential surface of the sleeve 50 in contact with the outer circumferential surface of the shaft 30, and a lower end portion is formed around the shaft 30. Axial directional pressure generating grooves 82 are formed on the upper surface of the cover plate 90 in contact with each other.

Meanwhile, although the conventional thrust bearing supports the shaft 30 coupled to the hub 10 and functions to prevent the separation, in the present invention, the conventional thrust bearing passes through the sleeve 50 to serve as the conventional thrust bearing. Fixing pin 100 to restrain the shaft 30 is further configured to replace.

In addition, the shaft 30 has a fixed groove 300 recessed inwardly along the outer circumferential surface at a predetermined position, has an oil gap and the fixing pin 100 is connected to the sphere of the shaft 30 At the same time serves as a guide, and when not driving will act as a restraining means for preventing the departure of the shaft (30).

In addition, in order to discharge the air particles from the oil gap to the outside, the fixing pin 10 has a shape of a pipe having an empty inside, and the air discharge groove 510 connected to the end thereof is a predetermined position of the sleeve 50. It will be formed in.

4 is a view for explaining a shaft and a sleeve according to the present invention, Figure 5 is a view for explaining a fixing pin and a cover plate according to the present invention.

First, referring to the shaft according to the present invention illustrated in FIG. 4 (a), cylindrical shapes having different outer diameters D1 and D2 are integrally formed, and a portion D1 having a small outer diameter is not shown in the drawing. It is inserted into the central insertion hole formed in the center of the hub is combined with the hub.

The shaft 30 according to the present invention forms a fixing groove 300 recessed inward in a predetermined position along its outer circumferential surface, which is connected to the fixing pin 100 to be described in FIG. When the shaft 30 rotates, it serves as a guide, and the role of restraining means for preventing the shaft 30 from being coupled with the hub is also combined. At this time, when the fixing pin 100 is connected to the fixing groove 300 of the shaft 30 to have an oil gap of a predetermined space.

On the other hand, Figure 4 (b) is a view showing a cross section of the sleeve 50 according to the present invention, the sleeve 50 is to insert the shaft 30 therein, at this time, the oil gap of a certain space It is to be able to fill the oil therein and to perform the role of the hydrodynamic bearing.

In addition, the sleeve 50 forms a predetermined groove 81 on the inner surface thereof. The sleeve 50 is formed in the shape of a herringbone or spiral so that the hub and the shaft 30 rotate in the oil gap. Filled oil is moved toward the center of the groove 81 by the pressure gradient to generate a fluid dynamic pressure to support the shaft 30 in the radial direction. In addition, the groove 81 formed on the inner surface of the sleeve 50 also serves to prevent the splashing of the fluid filled in the oil gap when the hub and shaft 30 rotates.

Here, the sleeve 50 forms a through hole 500 having a predetermined size penetrating the inside at a position corresponding to the fixing groove 300 of the shaft 30, which is the fixing pin 100 is Is inserted and received in the sleeve 500, a part is connected to the fixing groove 300 of the shaft 30 to prevent the departure of the shaft (30).

In addition, in order to discharge the air particles in the fluid to the outside, an air discharge groove 510 is formed on the outside of the sleeve 50 indented one side inward. One side of the air discharge groove 510 is connected to the through hole 500 so that air moves from the fixing pin 100 and air particles are discharged to the outside.

At this time, as shown in Figure 4 (c) as the number of the through-hole 500 and the air discharge groove 510 the fixing pin 100 should be formed to correspond to this. That is, one or more fixing pins 100 are provided. For example, when two fixing pins 100 are provided, through holes 500 and 500 'and air discharge grooves 510 and 510' that can accommodate them also correspond to the fixing pins 100. It should be formed in two places.

The fixing pin 100 shown in FIG. 5 (a) penetrates the through hole 500 of the sleeve 50 in the shape of a predetermined pin and pens the oil gap into the fixing groove 300 of the shaft 30. Is connected to have. That is, the fixing pin 100 is longer than the cross section of the sleeve 50, and thus the fixing pin 100 is inserted into the sleeve 50 and protrudes outside the sleeve 50 to receive It is divided into parts connected to the fixing groove 300 of the shaft 30.

On the other hand, the fixing pin 100 is empty inside the pipe shape to discharge the air particles from the oil gap to the outside, the air particles are moved from the front end to the end of the fixing pin 100, the sleeve connected thereto Air particles are discharged to the outside through the air discharge groove 510 of 50.

Cover plate 90 according to the present invention is for sealing the open portion of the sleeve 50, as shown in Figure 5 (b) grooves in a predetermined position of the upper surface which is in contact with the shaft 30 And (82). This will support the shaft 30 in the axial direction. In this case, the grooves 82 formed on the upper surface of the cover plate 90 are also preferably formed in the shape of a comb or spiral.

6 is a view for explaining dynamic pressure generation according to the present invention. As shown in FIG. 6, when the hub 10 rotates, the shaft 30 integrally coupled with the hub 10 rotates. The rotation of the hub 10 and the shaft 30 causes the dynamic pressure to be generated by the sleeves 50 and the grooves 81 and 82 formed on the cover plate 90 and the sleeve 50 supporting the hub 10 and the shaft 30. .

As shown in the enlarged view, the radial dynamic pressure F1 is generated by the radial dynamic pressure generating groove 81 formed on the upper and lower inner surfaces of the sleeve 50 in contact with the shaft 30, which is the shaft 30. ) To provide radial support.

In addition, the axial dynamic pressure F2 is generated by the axial dynamic pressure generating groove 82 formed on the upper surface of the cover plate 90 in contact with the lower end of the shaft 30, which supports the shaft 30 in the axial direction. Provide the power to do so.

At this time, the fixing pin 100 penetrates the sleeve 50 and is connected to the fixing groove of the shaft 30 to have an oil gap, and serves as a thrust bearing as a restraining means for preventing the detachment of the shaft. 50) Air particles present in the oil in the exhaust will be discharged to the outside.

That is, since the fixing pin 100 is hollow in a pipe shape, air particles are moved into the fixing pin 100 having low pressure from the oil gap therein, and the end of the fixing pin 100 is fixed. By moving to the air discharge groove 510 formed on the outer circumferential surface of the sleeve 50 is connected to the air particles are discharged to the outside.

When a small amount of air particles are present in the fluid through the gap between the hydrodynamic bearings, the air particles expand thermally as the temperature rises by frictional heat generated in the hydrodynamic bearing gaps at the beginning of the driving, and the expanded air particles The fluid may leak due to the fluid being pushed into the hydrodynamic bearing gap, which may damage the parts inside the hydrodynamic bearing, resulting in an increase in NRRO which is extremely fatal in driving characteristics.

Therefore, in the present invention, as well as the role of the conventional thrust bearing using the fixing pin also serves as a restraining means for preventing the departure of the shaft.

As described above, the present invention does not use the conventional thrust bearing, so that the verticality can be easily adjusted during the production of the product, thereby simplifying the assembly process, thereby lowering the production cost.

In addition, by applying the fixing pin according to the present invention, instead of acting as a restraining means of the conventional thrust bearing to prevent the departure of the shaft, and at the same time to discharge the air particles in the fluid to the outside, NRRO (Non) which is very fatal to the driving characteristics Prevents increase of Repeatadle Run Out, reduces driving load and lowers current consumption.

In the above, the present invention has been illustrated and described by way of specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the spirit of the present invention. Various changes and modifications may be made by the knowledgeable person.

Claims (3)

In a spindle motor for a hard disk drive using a hydrodynamic bearing, Hub 10 and the magnet 20 is installed on the inner side in the form of a cap open downward One side is coupled to the center of the hub 10, the shaft 30 is formed with a fixed groove 300 is recessed inward at a predetermined position in a predetermined position along the outer circumferential surface; A through hole having a predetermined size penetrating the inside at a position corresponding to the fixing groove 300 of the shaft 30 with an oil gap so that the shaft 30 is rotatable and rotatable ( A sleeve 50 forming a radial direction dynamic pressure generating groove 81 for forming a dynamic pressure on an inner surface thereof; Base 60 for fixing the sleeve 50; And A stator core (70) wound around a coil coupled to the base (60) to face the magnet (20); and A cover plate 90 which closes one side of the sleeve 50 and has an axial dynamic pressure generating groove 82 formed on an upper surface of the shaft 50 in contact with a lower surface of the shaft 30; And A fixing part consisting of; a fixing pin 100 penetrating through the through hole 500 of the sleeve 50 in a pin shape and connected to the fixing groove 300 of the shaft 30 to have an oil gap. Spindle motor for a hard disk drive comprising a. The method of claim 1, wherein the fixing pin 100 is It is provided with at least one, so that the through hole 500 of the sleeve 50 and the fixing groove 300 of the shaft 30 are respectively formed to correspond to the fixing pin 100; Spindle motor for disk drive. According to claim 1 or 2, wherein the fixing pin 100 is The air discharge groove 510 for discharging the air particles from the oil gap between the sleeve 50 and the shaft 30 in the shape of a hollow pipe and discharge it to the outside at a predetermined position of the outer peripheral surface of the sleeve 50 Formed on and connected to the fixing pin 100; spindle motor for a hard disk drive, characterized in that.

Images