KR20140033538A

KR20140033538A - Spindle motor

Info

Publication number: KR20140033538A
Application number: KR1020120091966A
Authority: KR
Inventors: 사토루 소데오카
Original assignee: 삼성전기주식회사
Priority date: 2012-08-22
Filing date: 2012-08-22
Publication date: 2014-03-19

Abstract

Disclosed is a spindle motor. The spindle motor comprises: a lower thrust member fixedly installed on a base member; a shaft of which a lower end portion is fixedly installed on the lower thrust member; an upper thrust member fixedly installed on an upper end portion of the shaft; a sleeve forming a bearing clearance along with the shaft and the upper and lower thrust members, and rotating around the shaft; and a rotor hub fixedly installed on the sleeve, and rotating in conjunction with the sleeve. A lower thrust dynamic pressure groove is formed in at least one of the top of the lower thrust member and the bottom of the sleeve disposed to face the top of the lower thrust member. An upper thrust dynamic pressure groove is formed in at least one of the bottom of the upper thrust member and the top of the sleeve disposed to face the bottom of the upper thrust member. A circulation hole inclined to prevent interference with the upper and lower thrust dynamic pressure grooves is formed in the sleeve.

Description

[0001] The present invention relates to a spindle motor,

The present invention relates to a spindle motor.

In general, a small spindle motor used in a hard disk drive (HDD) drives a disk to rotate so that a magnetic head can write or read data on the disk.

On the other hand, the shaft fixed spindle motor which fixed the shaft with strong impact resistance to the hard-disk drive apparatus is used. That is, in order to prevent the information recorded by an external shock from being damaged and being unable to record / read, a shaft fixed spindle motor in which a shaft is fixed is installed.

In addition, the spindle motor is provided with a fluid dynamic bearing assembly, and the bearing gap formed in the fluid dynamic bearing assembly is filled with lubricating fluid.

When the rotating member is rotated, the lubricating fluid filled in the bearing gap is pumped to form a fluid dynamic pressure to rotatably support the rotating member.

That is, in general, the hydrodynamic pressure bearing assembly generates dynamic pressure through a spiral thrust dynamic pressure groove in the axial direction and a radial dynamic pressure groove in the circumferential direction in the form of a harringbone, thereby stabilizing the motor rotation drive.

However, due to the pumping of the lubricating fluid at the time of rotation of the rotating member, in the bearing gap disposed inside the thrust dynamic groove and in the center of the radial dynamic groove, the pressure increases, but the pressure decreases. In this portion, a pressure lower than atmospheric pressure, that is, a negative pressure may be generated.

In this case, bubbles are formed as air components contained in the lubricating fluid come out, and when bubbles enter the grooves for pumping the lubricating fluid, sufficient fluid dynamic pressure is not generated and vibration is generated. .

In order to prevent this, the fluid dynamic bearing assembly is provided with a circulation hole that can reduce the generation of negative pressure.

Meanwhile, a gas-liquid interface may be formed in the upper and lower parts of the hydrodynamic bearing assembly provided in the spindle-type spindle motor. That is, the interface between the filled lubricating fluid and the air may be formed at the upper and lower portions of the bearing gap, respectively.

Then, in order to form a gas-liquid interface on the upper and lower portions, the rotating member should be provided with an inclined portion that is tapered.

However, in order to form the circulation hole so as not to interfere with the inclined portion and to form the circulation hole outside the upper and lower thrust dynamic pressure grooves, there is a problem in that the radial length of the rotating member is increased.

For this reason, there is a problem that the friction torque is increased and the rotational characteristics are also lowered.

Japanese Laid-Open Patent Publication No. 2005-003172

The present invention provides a spindle motor capable of suppressing a drop in the thrust fluid dynamic pressure caused by the circulation hole and at the same time an opening of the circulation hole outside the upper and lower thrust dynamic grooves, while suppressing an increase in the radial length of the sleeve.

Spindle motor according to an embodiment of the present invention is a lower thrust member fixedly installed on the base member, a shaft having a lower end fixed to the lower thrust member, an upper thrust member fixedly installed on the upper end of the shaft, the shaft And a bearing hub formed with the upper and lower thrust members, the sleeve being rotated about the shaft, and a rotor hub fixed to the sleeve to rotate in conjunction with the sleeve, and the upper surface of the lower thrust member. A lower thrust dynamic pressure groove is formed in at least one of the bottoms of the sleeves disposed opposite the upper surface of the lower thrust member, and at least one of a bottom surface of the upper thrust member and an upper surface of the sleeve disposed opposite the bottom surface of the upper thrust member. The upper thrust dynamic pressure groove is formed, the The sleeve may be provided with a circulation hole inclined to prevent interference with the upper and lower thrust dynamic pressure grooves.

One end of the circulation hole is opened to the upper surface of the sleeve, the other end of the circulation hole is opened to the bottom surface of the sleeve, and when the sleeve is cut to have a cross section parallel to the circulation hole one end of the circulation hole of the shaft It is disposed on one side and the other end of the circulation hole may be disposed on the other side of the shaft.

One end of the circulation hole may be opened to the upper surface of the sleeve to be disposed radially outward of the upper thrust dynamic pressure groove, and the other end of the circulation hole may be opened to the lower surface of the sleeve to be disposed radially outward of the lower thrust dynamic pressure groove. have.

The circulation hole communicates with a bearing gap formed by an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve, and may be formed as a single hole having a straight shape.

Upper and lower radial dynamic pressure grooves may be formed on the inner surface of the sleeve.

The upper radial dynamic grooves may pump the lubricating fluid to the upper side in the axial direction when the sleeve rotates, and the lower radial dynamic grooves may pump the lubricating fluid to the axial lower side in the rotation of the sleeve.

Since the circulation hole is formed so as not to interfere with the upper and lower thrust dynamic pressure grooves, there is an effect of suppressing the reduction of the thrust fluid dynamic pressure to improve the rotational characteristics.

In addition, while the opening of the circulation hole is formed in the sleeve so as to be disposed on the radially outer side of the upper and lower thrust dynamic pressure grooves, the opening of the circulation hole is inclined so as to be disposed on both sides of the shaft, thereby suppressing the increase in the radial length of the sleeve. have.

In addition, since the circulation hole is connected to the bearing gap formed by the outer circumferential surface of the shaft and the inner circumferential surface of the sleeve, negative pressure generation can be more effectively suppressed.

1 is a schematic sectional view showing a spindle motor according to an embodiment of the present invention.
Figure 2 is a partial cutaway perspective view showing a sleeve provided in the spindle motor according to an embodiment of the present invention.
Figure 3 is a plan view showing a sleeve provided in the spindle motor according to an embodiment of the present invention.
Figure 4 is a bottom view showing a sleeve provided in the spindle motor according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for clarity.

1 is a schematic cross-sectional view showing a spindle motor according to an embodiment of the present invention, Figure 2 is a partial cutaway perspective view showing a sleeve provided in the spindle motor according to an embodiment of the present invention, Figure 3 is one of the present invention 4 is a plan view illustrating a sleeve provided in the spindle motor according to the embodiment, and FIG. 4 is a bottom view illustrating the sleeve provided in the spindle motor according to the embodiment of the present invention.

1 to 4, the spindle motor 100 according to the embodiment of the present invention includes a base member 110, a lower thrust member 120, a shaft 130, an upper thrust member 140, and a sleeve ( 150 and rotor hub 160.

On the other hand, the spindle motor 100 according to an embodiment of the present invention may be a motor employed in an information recording and reproducing apparatus such as a hard disk driving apparatus as an example.

And, the spindle motor 100 according to an embodiment of the present invention may be largely composed of the stator 20 and the rotor 40.

The stator 20 refers to all fixing members except for the rotating member, and may include a base member 110, a lower thrust member 120, a shaft 130, and an upper thrust member 140. .

In addition, the rotor 40 refers to a member that rotates around the shaft 130 and may include a sleeve 150, a rotor hub 160, and the like.

Here, if the terms for the direction are first defined, the axial direction is an up and down direction, that is, a direction from the lower side to the upper side of the shaft 130 or the lower side from the upper side of the shaft 130 as shown in FIG. 1. In the direction shown in FIG. 1, the radial direction refers to the left and right directions, ie, the direction from the shaft 130 toward the outer circumferential surface of the rotor hub 160 or the shaft 130 from the outer circumferential surface of the rotor hub 160. Means the direction towards.

In addition, the circumferential direction means a direction that is rotated along the outer circumferential surface of the shaft 130 or the rotor hub 160.

The base member 110 is a fixed member included in the stator 20 rotatably supporting the rotor 40. In addition, the base member 110 may include a protrusion 112 extending toward the upper side in the axial direction.

On the other hand, the stator core 102 may be fixedly installed on the outer circumferential surface of the protrusion 112. To this end, the protrusion 112 may have a seating surface 112a on which the stator core 102 is seated.

The base member 110 may be made of an aluminum material by die-casting. In addition, the steel sheet may be molded into the base member 110 by plastic working (for example, press working).

The lower thrust member 120 is included in the fixing member, that is, the stator 20 together with the base member 110, and is fixed to the base member 110. That is, the lower thrust member 120 may be inserted into the protrusion 112, and more specifically, may be installed such that the outer circumferential surface of the lower thrust member 120 is joined to the inner circumferential surface of the protrusion 112.

In addition, the lower thrust member 120 may be bonded to the protrusion 112 by at least one of adhesion, welding, and indentation.

The lower thrust member 120 may include a body portion 122 having a disc shape and a sealing wall portion 124 extending in an axial direction from an edge of the body portion 122.

That is, the lower thrust member 120 may have a cup shape.

On the other hand, the inner surface of the body portion 122 of the lower thrust member 120 is bonded to the shaft 130. To this end, a mounting hole 122a for installing the shaft 130 may be formed in the body portion 122 of the lower thrust member 120. That is, the lower end of the shaft 130 is inserted into the mounting hole (122a).

In addition, the lower thrust member 120 may simultaneously serve as a sealing member for preventing leakage of the lubricating fluid.

Meanwhile, the sealing wall part 124 of the lower thrust member 120 serves to form the first gas-liquid interface F1 together with the lower end of the outer circumferential surface of the sleeve 150.

The shaft 130 is a fixing member constituting the stator 20 together with the base member 110, and has a lower end fixed to the lower thrust member 120. That is, as described above, the lower end of the shaft 130 may be inserted into the mounting hole 122a of the lower thrust member 120.

In addition, the lower end of the shaft 130 may be bonded to the lower thrust member 120 by at least one of adhesive, welding, and press-fitting.

However, in this embodiment, the case where the shaft 130 is fixed to the lower thrust member 120 is described as an example, but is not limited thereto. The shaft 130 may be fixed to the base member 110.

The upper thrust member 140 is a fixing member constituting the stator 20 together with the base member 110, the lower thrust member 120, and the shaft 130, and may be fixed to the upper end of the shaft 130. have.

The upper thrust member 140 may include a disc-shaped disc 142 and a protruding wall 144 extending downward from an edge of the disc 142 in the axial direction.

In other words, the upper thrust member 140 may have an upside down cup shape (upside down cup shape).

In addition, an insertion hole 142a may be formed in the disc 142 of the upper thrust member 140 so that the upper end of the shaft 130 may be inserted. That is, the upper end of the shaft 130 may be inserted into the insertion hole (142a).

Meanwhile, the upper thrust member 140 may also be joined to the upper end of the shaft 130 by at least one of adhesion, welding, and press fitting.

In addition, the protruding wall portion 144 of the upper thrust member 140 serves to form the second gas-liquid interface F2 together with the upper end of the outer circumferential surface of the sleeve 150.

In addition, the upper thrust member 140 may also simultaneously serve as a sealing member for preventing leakage of the lubricating fluid.

The outer circumferential surface of the upper thrust member 140 may be spaced apart from the inner circumferential surface of the rotor hub 160 by a predetermined interval to form a labyrinth seal. Thereby, evaporation of the lubricating fluid from the 2nd gas-liquid interface F2 can be suppressed.

The sleeve 150 is a rotating member that rotates around the shaft 130 and constitutes the rotor 40.

Meanwhile, the sleeve 150 forms a bearing gap together with the upper and lower thrust members 140 and 120 and the shaft 130. The bearing gap is filled with lubricating fluid.

In addition, a shaft hole 151 into which the shaft 130 is inserted may be formed in the sleeve 150. That is, the shaft 130 is inserted into the shaft hole 151, and thus the sleeve 150 may be rotated with the shaft 130 as the rotation center.

In addition, an upper thrust dynamic pressure groove 152 may be formed on an upper surface of the sleeve 150. In addition, the upper thrust dynamic pressure groove 152 serves to prevent the sleeve 150 from being injured during the rotation of the sleeve 150 and to allow the sleeve 150 to be rotated in a state of being raised to a certain height. .

In the present embodiment, the upper thrust dynamic groove 152 is described as an example in which the upper surface of the sleeve 150 is formed, but the present invention is not limited thereto, and the upper thrust dynamic groove 152 is disposed on the upper surface of the sleeve 150. It may be formed on the opposing surface of the upper thrust member 140 disposed to face. That is, the upper thrust dynamic pressure groove may be formed on the bottom surface of the disc portion 142 of the upper thrust member 140.

In addition, a lower thrust dynamic pressure groove 153 may be formed on the bottom of the sleeve 150. The lower thrust dynamic pressure groove 153 serves to provide a floating force in which the sleeve 150 floats when the sleeve 150 rotates.

Meanwhile, the lower thrust dynamic pressure groove 153 is not limited to the case where the lower thrust dynamic pressure groove 153 is formed on the bottom surface of the sleeve 150, and the lower thrust dynamic pressure groove 153 is disposed on the bottom surface of the sleeve 150. It may be formed on the upper surface. That is, the lower thrust dynamic pressure groove may be formed on the upper surface of the body portion 122.

In addition, the sleeve 150 may be formed with a circulation hole 154 that is inclined to prevent interference with the upper and lower thrust dynamic pressure grooves 152 and 153.

In addition, the circulation hole 154 may be formed of one hole having a straight shape.

Meanwhile, one end of the circulation hole 154 is opened to the top surface of the sleeve 150, and the other end thereof is opened to the bottom surface of the sleeve 150.

In addition, when the sleeve 150 is cut to have a cross section parallel to the circulation hole 154, one end of the circulation hole 154 is disposed on one side of the shaft 130, and the other end of the circulation hole 154 is the shaft 130. It may be disposed on the other side of the).

In other words, when the sleeve 150 is cut in the axial direction while passing through the center line of the sleeve 150 and the cutting surface is parallel to the circulation hole 154, one end of the circulation hole 154 is disposed on one side of the shaft 130. The other end of the circulation hole 154 may be disposed on the other side of the shaft 130.

That is, the circulation hole 154 is radially spaced apart from the cutting surface passing through the center line of the sleeve 150, but when the circulation hole 154 is projected to the cutting surface, the circulation hole 154 is the shaft hole 151 of the sleeve 150. It may be formed to be inclined to cross.

On the other hand, one end of the circulation hole 154 is opened to the upper surface of the sleeve 150 to be disposed radially outward of the upper thrust dynamic groove 152, the other end of the circulation hole 154 of the lower thrust dynamic groove 153 It may be open to the bottom of the sleeve 150 to be disposed radially outward.

Accordingly, the lowering of the thrust dynamic pressure generated from the upper and lower thrust dynamic pressure grooves 152 and 153 by the circulation hole 154 can be suppressed. That is, the circulation hole 154 may not be opened to the upper surface and the bottom surface of the sleeve 150 in a portion where the upper and lower thrust dynamic pressure grooves 152 and 153 are formed, thereby reducing the decrease in the thrust dynamic pressure.

In addition, since the opening of the circulation hole 154 is formed to be inclined to be disposed on one side and the other side of the shaft 130, an increase in the radial length of the sleeve 150 may be suppressed.

That is, the circulation hole 154 is formed to be parallel to the shaft 130 while being disposed in the radially outer side of the upper and lower thrust dynamic pressure grooves 152 and 153, and the sleeve for the formation of the first and second gas-liquid interfaces F1 and F2. The radial length of the sleeve 150 must be increased in order not to interfere with the inclined portion of the 150.

However, as described above, the opening of the circulation hole 154 is inclined so as to be disposed on one side and the other side of the shaft 130, so that the circulation hole 154 is disposed on the radially outer side of the upper and lower thrust dynamic pressure grooves 152 and 153. While not being able to interfere with the inclined portion of the sleeve 150 for the formation of the first and second gas-liquid interfaces F1 and F2.

In addition, it may not increase the radial length of the sleeve 150.

In addition, the circulation hole 154 may communicate with the bearing gap formed by the outer circumferential surface of the shaft 130 and the inner circumferential surface of the sleeve 150. That is, the circulation hole 154 may be formed such that the central portion of the circulation hole 154 communicates with the bearing gap.

Meanwhile, upper and lower radial dynamic pressure grooves 155 and 156 may be formed on the inner surface of the sleeve 150.

In addition, the upper radial dynamic pressure groove 155 pumps the lubricating fluid toward the upper side in the axial direction when the sleeve 150 rotates, and the lower radial dynamic pressure groove 156 pumps the lubricating fluid into the lower axial direction when the sleeve 150 rotates. can do.

Accordingly, when the sleeve 150 is rotated, the lubricating fluid may flow along respective circulation flows at the top and the bottom.

That is, the lubricating fluid pumped by the upper radial dynamic groove 155 flows along the circulation hole 154 after flowing to the bearing gap formed by the upper surface of the sleeve 150 and the upper thrust member 140. Thereafter, the lubricating fluid flows into the bearing gap formed by the shaft 130 and the sleeve 150 again at the portion where the circulation hole 154 and the shaft hole 151 are connected.

Then, the lubricating fluid pumped by the lower radial dynamic pressure groove 156 flows along the circulation hole 154 after flowing into the bearing gap formed by the bottom surface of the sleeve 150 and the lower thrust member 120. Thereafter, the lubricating fluid flows into the bearing gap formed by the shaft 130 and the sleeve 150 again at the portion where the circulation hole 154 and the shaft hole 151 are connected.

As such, another circulation flow may be formed at the lower side of the bearing gap by the lower radial dynamic pressure groove 156.

Meanwhile, the circulation hole 154 may communicate with a bearing gap disposed between the upper and lower radial dynamic grooves 155 and 156.

Accordingly, it is possible to reduce the generation of sound pressure in the bearing gap disposed between the upper and lower radial dynamic grooves 155 and 156.

The rotor hub 160 is a rotating member constituting the rotor 40 together with the sleeve 150, and is coupled to the outer circumferential surface of the sleeve 150 as described above.

The rotor hub 160 is formed from a disc-shaped rotor hub body 162, a magnet mounting portion 164 extending in an axial direction from an edge of the rotor hub body 162, and an end portion of the magnet mounting portion 164. The disk seating portion 166 extending in the radial direction and the coupling portion 168 extending downward in the axial direction from the inner diameter of the rotor hub body 162 may be provided.

On the other hand, a driving magnet 164a is installed on the inner surface of the magnet mounting portion 164, and the driving magnet 164a is disposed opposite to the tip of the stator core 102 on which the coil 101 is wound.

On the other hand, the driving magnet 164a may have a ring shape, and may be a permanent magnet in which N poles and S poles are alternately magnetized along the circumferential direction to generate a magnetic force of a predetermined intensity.

Here, when the rotation drive of the rotor hub 160 is briefly described, when the power is supplied to the coil 101 wound on the stator core 102, the driving magnet 164a and the stator core wound around the coil 101 ( The electromagnetic interaction with the 102 generates a driving force to rotate the rotor hub 160. Accordingly, the rotor hub 160 is rotated.

In addition, when the rotor hub 160 is rotated, the sleeve 150 is also rotated in conjunction with the rotor hub 160.

Accordingly, the lubricating fluid filled in the bearing gap is pumped by the upper and lower radial dynamic pressure grooves 155 and 156 and the upper and lower thrust dynamic pressure grooves 152 and 153 to generate fluid dynamic pressure. The rotor hub 160 may be more stably rotated by the fluid dynamic pressure generated as described above.

Meanwhile, in the present embodiment, the case in which the sleeve 150 and the rotor hub 160 are separately manufactured and combined is described as an example, but is not limited thereto. The sleeve 150 and the rotor hub 160 may be integrally formed. have.

As described above, since the circulation hole 154 is formed so as not to interfere with the upper and lower thrust dynamic pressure grooves 152 and 153, the reduction of the thrust fluid dynamic pressure can be suppressed to improve the rotational characteristics.

The opening of the circulation hole 154 is inclined so as to be disposed on one side and the other side of the shaft 130, so that the circulation hole 154 is disposed on the radially outer side of the upper and lower thrust dynamic pressure grooves 152 and 153, and thus the first and second gas liquids. It may not interfere with the inclined portion of the sleeve 150 for forming the interface (F1, F2).

In addition, it may not increase the radial length of the sleeve 150.

In addition, since the circulation hole 154 is connected to a bearing gap formed by the outer circumferential surface of the shaft 130 and the inner circumferential surface of the sleeve 150, it is possible to more effectively suppress sound pressure generation.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

100: Spindle motor
110: Base member
120: Lower thrust member
130: shaft
140: upper thrust member
150: sleeve
160: Rotor hub

Claims

A lower thrust member fixed to the base member;
A shaft having a lower end fixed to the lower thrust member;
An upper thrust member fixedly mounted on an upper end of the shaft;
A sleeve formed together with the shaft and the upper and lower thrust members to form a bearing gap, the sleeve being rotated about the shaft; And
A rotor hub fixed to the sleeve and rotated in association with the sleeve;
Including;
A lower thrust dynamic pressure groove is formed on at least one of an upper surface of the lower thrust member and a bottom surface of the sleeve disposed to face the upper surface of the lower thrust member;
An upper thrust dynamic pressure groove is formed on at least one of a bottom surface of the upper thrust member and an upper surface of the sleeve disposed to face the bottom surface of the upper thrust member.
The sleeve motor has a circulation hole is formed in the sleeve is disposed to be inclined to prevent interference with the upper, lower thrust dynamic pressure groove.

The method of claim 1,
One end of the circulation hole is opened to the upper surface of the sleeve, the other end of the circulation hole is opened to the bottom surface of the sleeve,
When the sleeve is cut to have a cross section parallel to the circulation hole, one end of the circulation hole is disposed on one side of the shaft and the other end of the circulation hole is disposed on the other side of the shaft.

3. The method of claim 2,
One end of the circulation hole is opened to the upper surface of the sleeve to be disposed on the radially outer side of the upper thrust dynamic groove, the other end of the circulation hole is opened to the lower surface of the sleeve to be disposed radially outward of the lower thrust dynamic groove of the spindle motor.

The method of claim 1,
The circulation hole is in communication with the bearing gap formed by the outer circumferential surface of the shaft and the inner circumferential surface of the sleeve, the spindle motor is formed as a single hole having a straight shape.

The method of claim 1,
Upper and lower radial dynamic pressure grooves are formed on the inner surface of the sleeve spaced apart.

6. The method of claim 5,
The upper radial dynamic groove pumps the lubricating fluid to the upper side in the axial direction when the sleeve rotates,
The lower radial dynamic pressure groove is a spindle motor for pumping the lubricating fluid to the lower side in the axial direction when the sleeve rotates.