JP2560507Y2 - Dynamic pressure bearing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrodynamic bearing device used for a spindle unit or the like and having a stator and a rotor.

[0002]

2. Description of the Related Art Conventionally, as a dynamic bearing device of this kind,
There is one shown in FIG. This dynamic pressure bearing device has a bottom plate 31.
A shaft 33 having a larger diameter than the shaft 32 is connected to the shaft 32 fixed to the shaft 32, and the shaft 33 is housed in a sleeve 35. On the outer peripheral surface of the shaft body 33 facing the sleeve 35, a U-shaped dynamic pressure groove 33a is provided. The sleeve 35 and the shaft 33 constitute a dynamic pressure generating unit. Shaft 33
The diameter of the dynamic pressure generating section is made larger than that of the shaft 32, so that the dynamic pressure generating area in which the dynamic pressure grooves 33a are provided is widened. It is designed to generate as much dynamic pressure as possible. On the other hand, the stator 37 is attached to the outer peripheral surface of the shaft 32, and the rotor 38 is attached to the inner peripheral surface of the sleeve 35 so as to face the stator 37. Sleeve 3 above
The magnet 41 is attached to the upper plate portion 35a of the fifth member 5. In addition, the magnet 42 is fixed to the shaft 33 so that the same pole faces the magnet 41.

When the rotor 38 and the sleeve 35 rotate integrally by the rotating magnetic field generated by the stator 37,
The dynamic pressure groove 33a provided on the shaft body 33 includes the sleeve 35 and the shaft body 3.
A dynamic pressure is generated in the air between the sleeve 35 and the sleeve 35 to support the sleeve 35 in the radial direction. The repulsive force of the magnets 41 and 42 supports the sleeve 35 in the axial direction.

[0004]

However, in the above-described conventional hydrodynamic bearing device, the shaft body 33 is provided only in one of the axial directions of the stator 37 attached to the shaft 32. Is small, and when a moment load is applied, the sleeve 35 and the shaft body 33 are likely to be one-sided. In addition, since the shaft body 33 has to have a large diameter, it is difficult to reduce the size.

Accordingly, an object of the present invention is to provide a dynamic pressure bearing device which is strong against a moment load and can be made compact.

[0006]

In order to achieve the above object, a hydrodynamic bearing device according to the present invention is provided with one of a stator and a rotor on an outer peripheral portion, and the stator or the rotor is provided at both axial sides of the one of the stator and the rotor. A shaft having first and second shaft portions, wherein the other of the stator or the rotor is provided on an inner peripheral portion, and a first bearing portion for supporting the first shaft portion and a second bearing portion for supporting the second shaft portion. A sleeve having two bearings, an outer diameter of the first shaft is smaller than an inner diameter of a stator or a rotor provided on an outer periphery of the shaft, and
The outer diameter of the second shaft portion is larger than the inner diameter of the rotor or the stator provided on the inner peripheral portion of the sleeve, and at least one of the outer peripheral surface of the first shaft portion or the inner peripheral surface of the first bearing portion, A dynamic pressure groove is formed on at least one of the outer peripheral surface of the second shaft portion and the inner peripheral surface of the second bearing portion.

[0007]

According to the above construction, the first and second shaft portions of the shaft and the first and second bearing portions of the sleeve form a dynamic pressure generating portion on both axial sides of the shaft. Therefore, due to the relative rotation between the shaft and the sleeve, dynamic pressure is generated on both axial sides of the stator or the rotor provided on the shaft. Therefore, compared to the conventional example in which the dynamic pressure is generated only on one side of the stator provided on the shaft in the axial direction, the stator is more resistant to the moment load. In addition, since it becomes strong against a moment load, the first and second shaft portions and the first and second bearing portions constituting the dynamic pressure generating portion can be reduced in size, and the dynamic pressure bearing device can be downsized. .

The outer diameter of the first shaft portion is smaller than the inner diameter of the stator or rotor provided on the outer peripheral portion of the shaft.
The shaft can be easily assembled from the shaft to the outer periphery of the shaft.

Further, the outer diameter of the second shaft portion is made larger than the inner diameter of the rotor or the stator provided on the inner peripheral portion of the sleeve, so that when the sleeve is mounted on the shaft, the second shaft portion is mounted. The second bearing portion facing the portion does not collide with the stator or rotor of the shaft. Therefore, the sleeve can be easily mounted on the shaft.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the hydrodynamic bearing device of the present invention. In this embodiment, a stator 2 is provided on the outer periphery of a shaft 1. The shaft 1 is provided with a first
While having the shaft portion 3, a second
It has a shaft 5. Dynamic pressure grooves 3a and 5a are formed on the outer peripheral surface of the first shaft portion 3 and the outer peripheral surface of the second shaft portion 5, respectively. The outer diameter of the first shaft portion 3 is smaller than the inner diameter of the stator 2. Therefore, the stator 2 can be easily assembled to the shaft 1 from the first shaft portion 3 side. Further, a ring-shaped permanent magnet 9 is attached to the step 6 of the shaft 1. The shaft 1 is fixed to a base 10.

The sleeve 7 is provided at its inner periphery with a rotor 8 facing the stator 2 provided on the shaft 1, and a first bearing 11 facing the first shaft 3 and a second bearing 5. And a second bearing portion 12 opposed thereto. In addition, the same pole as the permanent magnet 9 fixed to the step 6 is opposed to the inner peripheral surface of the sleeve 7 facing the step 6 of the shaft 1.
A ring-shaped permanent magnet 13 is attached. The magnet 9
And 13 support the sleeve 7 in the axial direction.

The outer diameter of the second shaft 5 of the shaft 1 facing the second bearing 12 of the sleeve 7 is larger than the inner diameter of the rotor 8. Therefore, when the sleeve 7 is mounted on the shaft 1, the second bearing 1 facing the second shaft 5
2 does not collide with the stator 2 of the shaft 1. Therefore, the sleeve 7 can be easily mounted on the shaft 1.

In the dynamic pressure bearing device, the first and second shaft portions 3, 5 of the shaft 1 and the first and second bearing portions 11, 12 of the sleeve 7 are provided on both sides of the shaft 1 in the axial direction. It constitutes a dynamic pressure generator. Accordingly, the rotating magnetic field generated by the stator 2 causes the rotor 8 and the sleeve 7 to rotate with respect to the shaft 1.
Are rotated integrally, the dynamic pressure grooves 3a and 5a are converted into air between the first bearing portion 11 and the first shaft portion 3 and air between the second bearing portion 12 and the second shaft portion 5. A dynamic pressure is generated to support the sleeve 7 in the radial direction. That is, the shaft 1
A dynamic pressure is generated on both sides of the stator 2 provided in the axial direction.
Therefore, according to this embodiment, compared to the conventional example in which the dynamic pressure is generated only on one side in the axial direction of the stator provided on the shaft,
Becomes strong against moment load. Further, for this reason, the first and second shaft portions 3, 5 and the first and second bearing portions 11, 12 constituting the dynamic pressure generating portion can be reduced in size.
The dynamic bearing device can be made more compact.

In the above embodiment, the dynamic pressure grooves 3a, 5a are formed on the outer peripheral surfaces of the first and second shaft portions 3, 5 of the shaft 1, but the first and second bearing portions 11, 5 of the sleeve 7 are formed. A dynamic pressure groove may be formed on the inner peripheral surface of the groove 12. Further, dynamic pressure grooves may be formed on both the outer peripheral surfaces of the shaft portions 3 and 5 and the inner peripheral surfaces of the bearing portions 11 and 12. Further, in the above embodiment, the stator 2 is provided on the shaft 1 and the rotor 8 is provided on the sleeve 7. However, the rotor may be provided on the shaft 1 and the stator may be provided on the sleeve 7.

[0016]

As is apparent from the above description, in the hydrodynamic bearing device of the present invention, the first and second shaft portions of the shaft and the first and second bearing portions of the sleeve are provided on the shaft. Dynamic pressure generating sections are formed on both sides of the stator or the rotor in the axial direction. Therefore, dynamic pressure is generated on both sides of the shaft in the axial direction due to the relative rotation between the shaft and the sleeve. Therefore, compared to the conventional example in which the dynamic pressure is generated only on one side in the axial direction of the stator or the rotor provided on the shaft, it is stronger against the moment load. In addition, since it becomes strong against a moment load, the first and second shaft portions and the first and second bearing portions constituting the dynamic pressure generating portion can be reduced in size, and the dynamic pressure bearing device can be downsized. Can be measured.

Further, since the first shaft portion has an outer diameter smaller than the inner diameter of the stator or rotor provided on the outer periphery of the shaft, the stator or rotor is moved from the first shaft portion side to the outer periphery of the shaft. Can be easily assembled.

Further, since the outer diameter of the second shaft portion is larger than the inner diameter of the rotor or the stator provided on the inner peripheral portion of the sleeve, when the sleeve is mounted on the shaft, the second shaft portion is mounted. The second bearing portion facing the portion does not collide with the stator or rotor of the shaft. Therefore, the stator can be easily mounted on the shaft.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a conventional hydrodynamic bearing device.

[Explanation of symbols]

 1,32 shaft 2,37 stator 3 first shaft 5 second shaft 6 step 7,35 sleeve 8,38 rotor 11 first bearing 12 second bearing

Claims (1)

(57) [Scope of request for utility model registration] An outer peripheral portion provided with one of a stator and a rotor, a shaft having first and second shaft portions on both sides in the one axial direction of the stator or the rotor, and an inner peripheral portion provided with the stator or the rotor; The other of the rotors is provided, comprising a first bearing portion for supporting the first shaft portion, and a sleeve having a second bearing portion for supporting the second shaft portion, wherein an outer diameter of the first shaft portion is the same as that of the shaft. The outer diameter of the second shaft portion is larger than the inner diameter of the rotor or stator provided on the inner circumferential portion of the sleeve, and the outer diameter of the second shaft portion is smaller than the inner diameter of the first shaft portion. A dynamic pressure groove formed on at least one of the outer peripheral surface or the inner peripheral surface of the first bearing portion and at least one of the outer peripheral surface of the second shaft portion or the inner peripheral surface of the second bearing portion. Pressure bearing device.