JPH1089348A - Fluid bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of lubricant splashing, oil film cutting and rubbing, and seizure due to the high speed rotation of a bearing. SOLUTION: A helical groove 11 is provided for the vicinity of a dynamic pressure generating groove 4C at the radial side in the inner circumferential surface at the open end part of a sleeve 4A. And the inner circumferential part of the sleeve 4A is filled with lubricant. Besides, a fixed shaft 2 is provided at the other end with a small diameter shaft smaller in diameter than the fixed shaft 2, and the helical groove 11 is provided for the inner circumferential part of a thrust plate 7 adjacent to the small diameter shaft. By this constitution, even when a motor is rotated, since lubricant is fed to the inner part side of the sleeve 4A by means of the pumping force of the helical groove 11, the lubricant of a fluid bearing will never be spread out, it is positively retained in the dynamic pressure generating groove, and stable rotation can thereby be assured for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure type hydrodynamic bearing device used for a disk recording device for recording and reproducing signals from a rotating magnetic disk.

[0002]

2. Description of the Related Art An example of a conventional hydrodynamic bearing device will be described below with reference to the drawings. FIG. 5 is a sectional view of a conventional hydrodynamic bearing device. 41 is a base, 42 is a shaft,
One end is fixed to the base 41, and the other end is a flange 43.
Has been fixed. A hub 44 having a sleeve 44A is rotatably mounted on the outer periphery of the shaft 42, and radial dynamic pressure generating grooves 44B and 44C are provided on the outer periphery of the shaft 42 or the inner periphery of the sleeve 44A. Also, the shaft 42
A thrust plate 47 is connected to the hub 44 so as to be opposed to and close to the flange 43 fixed to the other end of the hub. The thrust plate 47 has a thrust-side dynamic pressure generating groove 47A at a position opposed to the flange 43.
B, 44C and thrust-side dynamic pressure generating groove 47A
Is filled with. A motor stator 45 is provided on the base 41.
However, a motor rotor 46 is fixed to the hub 44. The hub 44 includes disks 48A and 48B and a spacer 49.
A has a shape that can be attached.

The operation of the conventional hydrodynamic bearing device configured as described above will be described below. First, when the motor stator 45 is energized and a rotating magnetic field is generated, the motor rotor 46 drives the hub 44 to rotate. At this time, the hub 44 includes the thrust plate 47, the disks 48A, 48
B, rotates with the spacer 49A. At this time, the radial-side dynamic pressure generating grooves 44B and 44C and the thrust-side dynamic pressure generating grooves 4
7A each generate pressure by pumping the lubricant 50, and the hub 44 floats and performs non-contact rotation.

The open end of the sleeve 44A is approximately 15
The tapered portion 51 forms a lubricant pool.

[0005]

However, the above configuration has the following problems. In FIG. 5, when the sleeve 44A rotates at a high speed, a centrifugal force acts on the lubricant 50 in the tapered portion 51, and the lubricant 50 flows out as shown in 50A, and the lubricant pool is emptied. Accordingly, the herringbone-shaped radial dynamic pressure generating groove 44C is used.
, Especially at the lower part (arrow A in the figure), the oil film breaks,
Occasionally, the image was worn out or burned in.

[0006]

In order to solve the above problems, a hydrodynamic bearing device according to the present invention has the following configuration.

That is, on the inner peripheral surface of the sleeve release end,
A helical groove is formed near the radial dynamic pressure generating groove. The radial dynamic pressure generating groove is filled with a lubricant.

Further, the other end of the fixed shaft has a small diameter shaft smaller in diameter than the fixed shaft outer diameter, and a helical groove is formed in an inner peripheral portion of a thrust plate through which the small diameter shaft passes.

According to the present invention, the lubricant is supplied to the radial-side dynamic pressure generating groove or the thrust-side dynamic pressure generating groove without causing the internal lubricant to flow out by the helical groove even during high-speed rotation. Does not cut. Further, since the lubricant on the outer peripheral portion of the small-diameter shaft is less likely to be scattered by centrifugal force, the same effect as described above can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a fixed shaft 2 is fixed to a base 1 at one end thereof. A hub 4 for fixing the disks 8A, 8B and the spacer 9A to the fixed shaft 2 is integrated with the sleeve 4A, and is rotatably fitted to the fixed shaft 2. A substantially ring-shaped flange 3 is fixed near the upper end side of the fixed shaft 2, and this flange 3 is
In the recess. Further, a thrust plate 7 is coupled to the hub 4 so as to be opposed to and close to the flange 3. At least two sets of, for example, herringbone-shaped radial dynamic pressure generating grooves 4B and 4C are provided on one of the outer peripheral surface of the fixed shaft 2 and the inner peripheral surface of the sleeve 4A, and the end surface of the flange 3 and the thrust plate 7 are provided. A thrust-side dynamic pressure generating groove 7A is provided on one of the opposing surfaces of
B, 4C and 7A are lubricated with a lubricant 10. A motor rotor 6 is fixed to the hub 4, and a motor stator 5 is fixed to the base 1. Further, a helical groove 11 is formed on the inner peripheral surface of the open end of the sleeve 4A near the radial-side dynamic pressure generating groove 4C.

The operation of the hydrodynamic bearing device configured as described above will be described. In FIG. 1, when a motor stator 5 is energized to generate a rotating magnetic field, a motor rotor 6 drives the hub 4 to rotate. At this time, the hub 4 rotates together with the thrust plate 7. At this time, the radial-side dynamic pressure generating grooves 4B and 4C and the thrust-side dynamic pressure generating groove 7A respectively generate pressure by pumping the lubricant 10 to cause the thrust plate 7 and the sleeve 4A to float and perform non-contact rotation. . At this time, as shown in FIG. 2, the lubricant 10 accumulated in the helical groove 11 is supplied to the radial-side dynamic pressure generating groove 4C by a pump force generated by rotation. During the stop, the lubricant 10 stays in the bearing due to surface tension.

As described above, according to the present embodiment, even when the motor is rotating, the lubricant 10 is supplied to the radial dynamic pressure generating groove 4C by the pumping force of the helical groove 11, so that the inside of the fluid bearing is The lubricant 10 is securely held in the radial-side dynamic pressure generating groove 4C without oozing out, and stable rotation can be obtained for a long period of time.

As shown in FIG. 3, the sleeve 4A has a tapered portion 11A between the radial dynamic pressure generating groove 4C and the helical groove 11 whose inner diameter decreases in the helical groove direction.
Is provided, the centrifugal force at the time of rotation is used, and the oil sealing performance is further improved, so that oil outflow can be completely prevented. Also, the radial-side dynamic pressure generating grooves 4B, 4C
Has been described on the inner periphery of the sleeve 4A, but may be formed on the outer peripheral surface of the fixed shaft 2.

In this embodiment, the sleeve 4
Although the case where the A and the hub 4 are separate members has been described, the same applies to a completely integrated product including a die-cast component, a press component, and the like.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In FIG. 4, the lower case 2
1, a fixed shaft 22 is fixed at one end, and the other end is a male screw or a projection 22A. Fixed shaft 2
2 has a hub 24 for fixing the disks 28A, 28B, 28C, 28D and the spacers 29A, 29B, 29C.
Are integrated with the sleeve 24A, and are rotatably fitted to the fixed shaft 22. A substantially ring-shaped flange 23 is fixed near the upper end side of the fixed shaft 22, and the flange 23 is housed in a concave portion of the hub 24. A thrust plate 27 is fixed to the hub 24 by a ring 33 together with an O-ring 34 so as to be opposed to and close to the flange 23. At least two sets of, for example, herringbone-shaped radial-side dynamic pressure generating grooves 24B and 24C are provided on one of the outer peripheral surface of the fixed shaft 22 and the inner peripheral surface of the sleeve 24A. 23
The lower thrust dynamic pressure generating groove 2
3A, the flange 23 and the thrust plate 2
An upper thrust dynamic pressure generating groove 27A is provided on one of the opposing surfaces 7. Each groove 23A, 24
B, 24C and 27A are filled with the lubricant 30.
A motor rotor 26 is fixed to the hub 24, and a motor stator 25 is fixed to the lower case 21. The male screw or the convex portion 22 </ b> A above the fixed shaft 22 is attached to the upper cover 11 by a nut or a ring-shaped member 32.
Further, a helical groove 35 is provided in the inner peripheral portion of the thrust plate 27 adjacent to the other end of the fixed shaft 22. The inner peripheral portion of the sleeve 24A is filled with the lubricant 30.

The operation of the hydrodynamic bearing device configured as described above will be described. In FIG. 4, when a motor stator 25 is energized and a rotating magnetic field is generated, the motor rotor 26 comprises a hub 24, a sleeve 24A, a thrust plate 2
7. Start rotating with disks 28A, 28B, 28C, 28D and spacers 29A, 29B, 29C. At this time, the radial side dynamic pressure generating grooves 24B and 24C
The lower thrust dynamic pressure generating groove 23A and the upper thrust dynamic pressure generating groove 27A also collect the lubricant 30, and the rotation of the sleeve 24A, the thrust plate 27, etc. is generated by the generated pressure. The body is firmly fixed to the hub 24 together with the O-ring 34 by a ring 33, and a helical groove 35 is provided on the inner periphery of the thrust plate 27.
Can be prevented from flowing out. Thrust plate 27
May be smaller than the maximum diameter of the fixed shaft 22. In this case, as the diameter D of the shaft facing the inner peripheral portion of the thrust plate 27 is smaller, the lubricant existing on the outer peripheral portion is less likely to be scattered by centrifugal force, and is held at a necessary portion of the bearing. . Further, a helical groove 36 having the same shape as the helical groove 11 in the first embodiment shown in FIGS.

As described above, according to the present embodiment, even when the motor is rotating, the lubricant of the fluid bearing is securely held in the dynamic pressure generating grooves without being scattered or oozing out due to centrifugal force or the like. And stable rotation is obtained over a long period of time.

Although the radial dynamic pressure generating grooves 4B and 4C have been described as being formed on the inner periphery of the sleeve 24A, the same applies to the case where they are formed on the outer peripheral surface of the fixed shaft 22.

In this embodiment, the sleeve 2
Although the case where the 4A and the hub 24 are separate members has been described, the same applies to a completely integrated member including a die-cast component, a press component, and the like.

[0021]

As described above, according to the present invention, by forming a helical groove at the open end of the sleeve or the inner peripheral surface of the thrust plate, it is possible to prevent the lubricant from flowing out and to cause oil film breakage, wear, and seizure. Without this, the reliability of the rotating device can be greatly improved. In addition, by reducing the diameter of the shaft facing the inner peripheral portion of the thrust plate, the lubricant existing on the outer peripheral portion is less likely to be scattered by centrifugal force, and the same effect as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydrodynamic bearing device according to an embodiment of the present invention.

FIG. 2 is a detailed view of a sleeve of the hydrodynamic bearing device shown in FIG.

FIG. 3 is a detailed view of a sleeve of the hydrodynamic bearing device shown in FIG. 1;

FIG. 4 is a sectional view of a hydrodynamic bearing device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional hydrodynamic bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Fixed shaft 3 Flange 4 Hub 4A Sleeve 4B, 4C Radial side dynamic pressure generating groove 4D Small inner diameter part 5 Motor stator 6 Motor rotor 7 Thrust plate 7A Thrust side dynamic pressure generating groove 8A, 8B, 8C Disk 9A, 9B Spacer 10 Lubricating oil 11 Helical groove 11A Taper portion 21 Lower case 22 Fixed shaft 22A Male screw or convex portion 23 Flange 23A Lower thrust dynamic pressure generating groove 24 Hub 24A Sleeve 24B, 24C Radial dynamic pressure generating groove 25 Motor stator 26 Motor rotor 27 Thrust plate 27A Upper thrust dynamic pressure generating groove 28A, 28B, 28C, 29C Spacer 30 Lubricant 31 Upper cover 32 Nut or ring-shaped member 33 Ring 34 O-ring 35 Helical groove 36 Helical groove

Claims (3)

[Claims] 1. A fixed shaft having at least one end fixed to a case, a flange member fixed near the other end of the fixed shaft, and a sleeve rotatably inserted into the fixed shaft. A thrust plate fixed near the end face of the sleeve or the end face of the sleeve, opposed to and adjacent to the flange member, and having a radial side on at least one of the outer peripheral surface of the fixed shaft or the inner peripheral surface of the sleeve. A dynamic pressure generating groove, and a thrust-side dynamic pressure generating groove on one of the opposing surfaces of the flange member and the thrust plate; A lubricant is held in a groove portion of the groove, a motor stator is provided in the case, a motor rotor is provided in the hub, and a helical groove is provided in an inner peripheral surface of the sleeve at an open end of the sleeve. A fluid bearing device, wherein the inner peripheral surface of the sleeve is filled with a lubricant. 2. A fixed shaft having at least one end fixed to a case, a flange member fixed near the other end of the fixed shaft, and a sleeve rotatably inserted into the fixed shaft. A thrust plate fixed near the end face of the sleeve or the end face of the sleeve, opposed to and adjacent to the flange member, and having a radial side on at least one of the outer peripheral surface of the fixed shaft or the inner peripheral surface of the sleeve. A dynamic pressure generating groove, and a thrust-side dynamic pressure generating groove on one of the opposing surfaces of the flange member and the thrust plate; A lubricant is held in a groove portion of the groove, a motor stator is provided in the case, and a motor rotor is provided in the hub, and an outer diameter of a portion of the fixed shaft penetrating the thrust plate is defined as A fluid bearing device having a diameter smaller than a maximum outer diameter of a fixed shaft and having a helical groove in an inner peripheral portion of the thrust plate through which the fixed shaft passes. 3. The hydrodynamic bearing device according to claim 2, wherein a helical groove is formed on an inner peripheral surface of the sleeve at an open end of the sleeve, and the inner peripheral surface of the sleeve is filled with a lubricant.