JPH07259849A - Dynamic pressure bearing - Google Patents

Abstract

PURPOSE:To prevent a peripheral part of a rotary unit, particularly increased with a rotational speed, from coming into contact with a thrust bearing, even in the case of setting the rotary unit tilted or setting it up horizontally. CONSTITUTION:A device has a radial bearing 4, thrust bearing 2, 3 provided in both ends of the radial bearing 4 and a rotary unit 5 rotatably provided in the radial bearing 4 and the thrust bearings 2, 3. At the time of rotating the rotary unit 5 received by the radial bearing and the thrust bearings, a minimum value of clearance width, generated between the rotary unit and the thrust bearing, is increased larger than a minimum value of clearance width generated between the radial bearing and the rotary unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a dynamic pressure generating groove between a rotating body and a non-rotating body, and the rotation of the rotating body causes the dynamic pressure generating groove to act between the rotating body and the non-rotating body. The present invention relates to a dynamic pressure bearing of a rotary machine that enables high speed rotation of a rotating body by forming a gap.

[0002]

2. Description of the Related Art In general, horizontal installation is the basis for installing a rotating body using a dynamic pressure bearing. The dynamic pressure bearing introduces the wind generated by the high speed rotation of the rotating body into the dynamic pressure generating groove provided in the non-rotating body, and the wind generates a stronger wind pressure than the dynamic pressure generating groove on the surface of the rotating body. By applying an air gap between the non-rotating body surface and the rotating body surface to form an air gap of several μm unit, the resistance between the non-rotating body and the rotating body is reduced,
It enables high-speed rotation of the rotating body. The rotating body as described above was used for the fixed radial bearing and the polygon mirror that rotates at a high rotation speed of 3000 rpm or more while floating in the air gap of several μm unit from the dynamic pressure generating groove provided in the thrust bearing. Dynamic bearings are also known.
No. 5-16574).

[0003]

If the dynamic pressure bearing as described above is installed horizontally as described above, it will not be affected by the rotation of the rotating body and the wind generated by the dynamic pressure generating groove as described above. The rotating body can maintain the rotation while maintaining an air gap of several μm between the rotating body. When the rotating body using the dynamic pressure bearing is used for rotating a polygon mirror for laser exposure used in, for example, a small printer, an image recording device, etc., the horizontal arrangement is unsatisfactory due to the installation location or the arrangement of parts. It may be possible. Therefore, when the dynamic pressure bearing is tilted according to the installation location together with the rotating body having the polygon mirror, the air gaps formed by the dynamic pressure generating grooves as described above are maintained at intervals of several μm. In some cases, a part of the rotating body may come into contact with the facing surface.
As described above, the polygon mirror rotates at a rotation speed of 3000 rpm or more, and particularly, the rotation speed of the rotation peripheral portion is higher than the rotation center portion of the rotating body. When the rotating body is arranged in an inclined manner as described above, or due to an external factor such as vibration, it cannot be held by the air gap, and there is a drawback that the peripheral portion of the rotating body contacts a part of the thrust bearing.

The present invention has been particularly devised in order to remedy the above-mentioned drawbacks. That is, of the radial bearing that receives the rotating body and the thrust bearing, the dynamic pressure bearing is configured so that the gap between the rotating body and the thrust bearing can be set wider than the gap between the rotating body and the radial bearing, and the rotating body is inclined. In the set state, and even in the case of horizontal installation,
The object is to prevent the peripheral portion of the rotating body whose rotational speed is particularly increased from coming into contact with the thrust bearing.

[0005]

In order to achieve the above-mentioned object, the present invention comprises, in claim 1, a radial bearing and thrust bearings provided at both ends of the radial bearing, and the radial bearing, In a dynamic pressure bearing having a rotating body rotatably provided in the thrust bearing, when the rotating body receives and rotates with the radial bearing and the thrust bearing,
The minimum value of the gap width generated between the rotary body and the thrust bearing is larger than the minimum value of the gap width generated between the radial bearing and the rotary body. 3. The dynamic pressure bearing according to claim 2, wherein a dynamic pressure generating groove is formed in both or at least one of the radial bearing and the thrust bearing. In Claim 3, When the said rotary body contacts the said bearing, it contacts at least a radial bearing with a small peripheral speed. The radial bearing according to claim 4, wherein the radial bearing is made of ceramics. The dynamic pressure bearing according to claim 5, further comprising a radial bearing and thrust bearings provided at both ends of the radial bearing, and the radial bearing and the rotating body rotatably provided on the thrust bearing. In addition, when the rotating body receives and rotates between the radial bearing and the thrust bearing, the minimum value of the gap width generated between the rotating body and the thrust bearing is equal to the minimum gap width generated between the radial bearing and the rotating body. A dynamic pressure bearing having a diameter larger than the minimum value, wherein the radial bearing and the rotary body are formed with a dynamic pressure generating groove. In claim 6,
When the rotating body comes into contact with the bearing, it should come into contact with at least a radial bearing having a low peripheral speed. The radial bearing according to claim 7, wherein the radial bearing is made of ceramics. The dynamic pressure bearing according to claim 8, further comprising a radial bearing and a thrust bearing provided at one end of the radial bearing, the radial bearing and the rotating body rotatably provided on the thrust bearing. In addition, when the rotating body receives and rotates between the radial bearing and the thrust bearing, the minimum value of the gap width generated between the rotating body and the thrust bearing is equal to the minimum gap width generated between the radial bearing and the rotating body. Must be greater than the minimum value. 10. The dynamic pressure bearing according to claim 9, wherein a dynamic pressure generation groove is formed in both or at least one of the radial bearing and the thrust bearing. In Claim 10, When the said rotary body contacts the said bearing, it contacts at least a radial bearing with a small peripheral speed. In Claim 11, it is achieved by forming the radial bearing from ceramics.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a rotary support device 1 for a polygon mirror. The rotary support device 1 is provided with plate-like thrust bearings 2 and 3 on the upper and lower sides, and is circled so as to be sandwiched between the thrust bearings 2 and 3. A dynamic pressure bearing 11 to which a columnar radial bearing 4 is fixed is provided. And the guide surfaces 21 and 31 of the thrust bearings 2 and 3,
The guide surface 41 of the radial bearing 4 has grooves 22 and 3 for generating dynamic pressure, respectively.
Form 2, 42. The rotating body 5 is provided with facing surfaces 51, 52, 53 rotatably formed with respect to the guide surfaces 21, 31, 41, and the rotating body 5 is provided with the radial bearing 4 as a center of rotation. The polygon mirror 7 is fixedly provided on the outer periphery of the rotating body 5 together with the mounting members 6 and 61. The mounting member 6 is provided with a stator coil 6A, and the rotation support device 1 is provided with a magnet 8 facing the stator coil 6A. By energizing the stator coil 6A, the rotating body 5 is induced to rotate at a high speed. Let

FIG. 2 shows a gap between the thrust bearings 2 and 3 and the radial bearing 4 when the rotating body 5 rotates. Guide surfaces 21 and 31 in which the dynamic pressure generating grooves 22 and 32 of the thrust bearings 2 and 3 are formed, and the rotor 5
The distance between the facing surfaces 51 and 52 facing the guide surfaces 21 and 31 is 5 to 7
The dynamic pressure generating grooves 22, 32, 42 are formed so as to maintain an air gap of 1 to 3 μm between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5. When the rotating body 5 and the polygon mirror 7 are rotated at a high speed by the above setting, even if the rotational position of the rotating body 5 is slightly displaced due to the tilted arrangement or vibration as described above, the thrust bearings 2 and 3 are The facing surfaces 51 and 52 of the rotating body 5 do not contact the guide surfaces 21 and 31, and the facing surface 53 of the rotating body 5 is the guide surface of the radial bearing 4.
It only makes some contact with 41. The radial bearing 4 may be formed of a ceramic material or the like to prevent abrasion and heat generation due to contact.

Similar to FIG. 2, FIG. 3 shows the thrust bearings 2, 3 as a gap between the thrust bearings 2, 3 and the radial bearing 4 when the rotor 5 rotates.
5 to 7 μm between the guide surfaces 21 and 31 of the rotary body 5 and the facing surfaces 51 and 52 of the rotary body 5 that face the guide surfaces 21 and 31, and the guide surface 41 of the radial bearing 4 and the facing surface of the rotary body 5 are 1 to 53
The dynamic pressure generating groove 2 so as to maintain an air gap of 3 μm
2, 32, 42 are formed. In this embodiment, the dynamic pressure generating grooves provided on the guide surfaces 21 and 31 of the thrust bearings 2 and 3 are used.
Instead of 22, 32, the dynamic pressure generating grooves 511, 521 are provided on the facing surfaces 51, 52 of the rotating body 5. With the above construction, the thrust bearing 2 can be used even when the rotating body 5 and the polygon mirror 7 are rotated at a high speed, or when the rotational position of the rotating body 5 is slightly displaced due to the inclined arrangement or the vibration as described above. The facing surfaces 51 and 52 of the rotating body 5 do not contact the guide surfaces 21 and 31 of the rotating body 5, and the facing surface 53 of the rotating body 5 only slightly contacts the guide surface 41 of the radial bearing 4. Incidentally, the radial bearing 4
Can be formed of a ceramic material or the like to prevent abrasion and heat generation due to contact.

FIG. 4 shows another embodiment of FIG. 2 in which only the thrust bearing 2 of the thrust bearings 2 and 3 is provided. Also in this embodiment, the thrust bearing 2
5 between the guide surface 21 and the facing surface 51 facing the rotating body 5.
˜7 μm, and the dynamic pressure generating grooves 22, 42 are formed so as to maintain an air gap of 1 to 3 μm between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5. In this embodiment, the dynamic pressure generating groove 22 provided on the guide surface 21 of the thrust bearing 2 and the dynamic pressure generating groove of the radial bearing 4 are provided.
By 42, even when the rotating body 5 and the polygon mirror 7 are rotated at a high speed in the same manner as described above, the thrust bearing 2 is guided even if the rotational position of the rotating body 5 is slightly displaced due to the inclined arrangement or the vibration as described above. The facing surface 51 of the rotating body 5 does not contact the surface 21, but the facing surface 53 of the rotating body 5 only slightly contacts the guide surface 41 of the radial bearing 4. The radial bearing 4 may be formed of a ceramic material or the like to prevent abrasion and heat generation due to contact.

FIG. 5 shows the clearance condition when the rotor 5 rotates with respect to the radial bearing 4 and the thrust bearings 2 and 3 of the dynamic pressure bearing 11 shown in FIG. R ₁ and R ₂ are provided between the guide surface 41 and the facing surface 53 of the rotating body 5, and t ₁ and t ₂ are provided between the guide surfaces 21 and 31 of the thrust bearings ₂ and 3 and the facing surface 51 and 52 of the rotating body 5, respectively. And When t ₁ <t ₂ and R ₁ <R ₂ when the rotating body 5 rotates, t ₁ > R ₁
To be set.

In FIGS. 1, 2, 3 and 5 of the above embodiment, the dynamic pressure generating grooves 22 and 32 provided on the guide surfaces 21 and 31 of the thrust bearings 2 and 3 are, for example, one guide. Surface 21 or guide surface 31
You may provide only in. Further, the dynamic pressure generating groove 51 of the rotating body 5
1,521 may be provided on only one side.

FIGS. 6A and 6B show another embodiment of FIG. In FIG. 6A of this embodiment, the guide surfaces 21 and 31 of the thrust bearings 2 and 3 are inclined surfaces 211 and 311. That is, the inclined surfaces 211 and 311 are inclined outwardly with respect to the facing surfaces 51 and 52 of the rotating body 5 provided with the polygon mirror 7 outwardly from the guide surface 41 of the radial bearing 4. The maximum distance between the thrust bearings 2 and 3 caused by the inclination is set to 2 to 5 μm. The distance between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5 is 1 to 3 μm, as in the case of FIG. Therefore, in particular, the facing surface 5
The outer peripheral positions of the 1st and 52nd surfaces are arranged so as to be farther from the inclined surfaces 211 and 311. Next, in FIG. 6B of the present embodiment, the guide surfaces 21, 31 in the thrust bearings 2, 3 are curved inclined surfaces 212, 312. That is, the inclined surfaces 212 and 312 are inclined in a curved shape so as to be gradually separated from the facing surface 51 and 52 outward from the guide surface 41 of the radial bearing 4, and the thrust bearings 2 and 3 of the thrust bearings 2 and 3 caused by the inclination. Maximum distance is 2
~ 5 μm. The distance between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5 is 1 to 3 μm as in the case of FIG.
And Therefore, as in the case of FIG. 6A, the facing surface 51,
The outer peripheral position of the 52 surface is configured to be farther from the curved inclined surfaces 212 and 312.

6 (a) and 6 (b) configured as described above.
In the above embodiment, the rotating body 5 provided with the polygon mirror 7
Radial bearing 4 when rotating at a speed of 3000 rpm or more
In the dynamic pressure generating groove 42 provided in the
Rotate while maintaining a gap of ~ 3 μm. At this time, as described above, even if the dynamic pressure bearing 11 is installed in an inclined manner or vibration occurs, the facing surfaces 51, 52 of the rotating body 5 will not move to the thrust bearing 2, 2.
It does not contact the outer peripheral portions of the inclined surfaces 211, 311, 212, and 312 that are formed so as to be inclined at 3.

FIGS. 7A and 7B show another embodiment of FIG. In FIG. 7A of this embodiment, the facing surfaces 51 and 52 of the rotating body 5 provided with the polygon mirror 7 are inclined surfaces 511 and 521. That is, the inclined surfaces 511 and 521 are inclined so as to be gradually separated outward with respect to the guide surfaces 21 and 31 of the thrust bearings 2 and 3, and the maximum distance of the rotating body 5 caused by the inclination is 2 to 5 μm. . The space between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5 is the same as in FIG.
1 to 3 μm as in the above. Therefore, in particular, the outer peripheral portion of the rotor 5 is configured to be largely separated from the guide surfaces 21 and 31 of the thrust bearings 2 and 3 by the inclination. In FIG. 7B, the facing surfaces 51 and 52 of the rotating body 5 provided with the polygon mirror 7 are curved inclined surfaces 512 and 522. That is, the curved inclined surfaces 512 and 522 are inclined so as to be gradually separated outward with respect to the guide surfaces 21 and 31 of the thrust bearings 2 and 3, and the maximum distance of the rotating body 5 caused by the inclination is set to 2
~ 5 μm The distance between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5 is 1 to 3 μm as in the case of FIG.
And Therefore, in particular, the guide surface 2 of the thrust bearings 2, 3
The outer peripheral portion of the rotating body 5 is configured so as to be largely separated by the inclination from 1, 31.

7 (a) and 7 (b) configured as described above.
In the embodiment, the rotating body 5 provided with the polygon mirror 7
Radial bearing 4 when rotating at a speed of 3000 rpm or more
In the dynamic pressure generating groove 42 provided in the
Rotate while maintaining an interval of ~ 3 μm. At that time, as described above, even if the dynamic pressure bearing 11 is installed at an inclination or vibration occurs, the inclined surface 51 formed on the facing surfaces 51 and 52 of the rotating body 5
1,521,512,522 are guide surfaces 21,31 of thrust bearings 2,3
Does not touch the outer periphery of the.

FIG. 8 shows the above-mentioned FIG. 2, FIG. 3, FIG. 4, and FIG.
(A), (b), other embodiments of FIGS. 7 (a), (b),
The guide surfaces 21 and 31 of the thrust bearings 2 and 3 are inclined surfaces 213 and 313. That is, the inclined surfaces 213 and 313 are inclined outwardly with respect to the facing surfaces 51 and 52 of the rotating body 5 provided with the polygon mirror 7 outwardly from the guide surface 41 of the radial bearing 4. Let The distance between the guide surface 41 of the radial bearing 4 and the facing surface 53 of the rotating body 5 is 1 to 3 μm, as in the case of FIG. Also, the polygon mirror 7
The facing surfaces 51 and 52 of the rotating body 5 provided with are the curved inclined surfaces 513 and 523. That is, the curved inclined surface 51
3, 523 are the inclined surfaces 213, 313 of the thrust bearings 2, 3
On the other hand, it is inclined in a curved shape so as to be gradually separated outward. The outer peripheral end of the rotor 5 caused by the two-direction inclination of the inclined surfaces 213 and 313 of the thrust bearings 2 and 3 and the curved inclined surfaces 513 and 523 of the rotor 5, and the inclined surfaces 213 of the thrust bearings 2 and 3, The outer peripheral edges of 313 are largely separated, and the maximum distance is 4 to 10 μm. Therefore, in particular, the outer peripheral positions of the rotating bodies 5 are configured to be largely separated from each other.

In the embodiment of FIG. 8 configured as described above, when the rotating body 5 provided with the polygon mirror 7 is rotated at a rotation speed of 3000 rpm or more, the dynamic pressure generating groove 42 provided in the radial bearing 4 is formed. Then, the facing surface 53 of the rotating body 5 rotates while maintaining the interval of 1 to 3 μm. At that time, even if the dynamic pressure bearing 11 is installed at an inclination as described above, or even if vibration is generated, the curved inclined surfaces 513 and 523 formed on the rotating body 5 and the inclined surfaces 213 of the thrust bearings 2 and 3 are formed. , 313 does not touch the outer periphery.

[0018]

As described above, in the dynamic pressure bearing according to the present invention, compared with the air gap between the thrust bearing and the rotating body, the air between the facing surfaces of the rotating body facing the radial bearing serving as the central axis is increased. The structure is designed to reduce the gap, especially to prevent the contact between the rotor surface and the thrust bearing in the outer peripheral direction where the speed of the rotor increases, so that the rotor equipped with a polygon mirror etc. does not contact the thrust bearing. It is possible to prevent "galling" (a state in which the rotating body and the bearing are in contact with each other and the contact surfaces thereof are damaged or seized). Therefore, even if the rotary body provided with the polygon mirror is installed as tilted as necessary, or even if vibration is applied from the outside, stable rotation can be maintained for a long period of time at a rotation speed of 3000 rpm or more.

Further, the image forming apparatus or printer using the polygon mirror having the increased number of revolutions is configured to further improve the image quality, output at high speed, and contact at a position with low peripheral speed. Therefore, the energy of the "galling" is lowered, so that the range of selection of the bearing material is widened, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a polygon mirror using a dynamic pressure bearing of the present invention.

FIG. 2 is a cross-sectional view showing a dynamic pressure bearing of the present invention and respective gap values.

FIG. 3 is a cross-sectional view of another embodiment showing the dynamic pressure bearing of the present invention and each gap value.

FIG. 4 is a sectional view of another embodiment showing the dynamic pressure bearing of the present invention and each gap value.

FIG. 5 is a cross-sectional view showing the dynamic pressure bearing of the present invention and setting of each gap value.

FIG. 6 is a sectional view showing another embodiment of the dynamic pressure bearing of the invention.

FIG. 7 is a sectional view showing another embodiment of the dynamic pressure bearing of the invention.

FIG. 8 is a sectional view showing another embodiment of the dynamic pressure bearing of the invention.

[Explanation of symbols]

 1 Rotating support device for polygon mirror 2,3 Thrust bearing 4 Radial bearing 5 Rotating body 7 Polygon mirror 22, 32, 42, 511, 521 Dynamic pressure generating groove 21, 31, 41 Guide surface 51, 52, 53 Opposing surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyoji Ito 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company

Claims (11)

[Claims] 1. A radial bearing, and thrust bearings provided at both ends of the radial bearing, and the radial bearing,
In a dynamic pressure bearing having a rotating body rotatably provided in the thrust bearing, a gap generated between the rotating body and the thrust bearing when the rotating body receives and rotates by the radial bearing and the thrust bearing. A dynamic pressure bearing, wherein a minimum value of the width is larger than a minimum value of a gap width generated between the radial bearing and the rotating body. 2. The dynamic pressure bearing according to claim 1, wherein in the dynamic pressure bearing, a dynamic pressure generating groove is formed in both or at least one of the radial bearing and the thrust bearing. bearing. 3. The hydrodynamic bearing according to claim 1, wherein when the rotating body comes into contact with the bearing, it comes into contact with a radial bearing having a low peripheral speed. 4. The dynamic pressure bearing according to claim 1, wherein the radial bearing is made of ceramics. 5. A radial bearing, and thrust bearings provided at both ends of the radial bearing, and the radial bearing,
In a dynamic pressure bearing having a rotating body rotatably provided in the thrust bearing, a gap generated between the rotating body and the thrust bearing when the rotating body receives and rotates by the radial bearing and the thrust bearing. A dynamic pressure bearing having a minimum width larger than a minimum gap width generated between the radial bearing and the rotating body, wherein a dynamic pressure generating groove is formed in the radial bearing and the rotating body. A dynamic pressure bearing characterized in that 6. The dynamic pressure bearing according to claim 5, wherein when the rotating body comes into contact with the bearing, it comes into contact with at least a radial bearing having a low peripheral speed. 7. The dynamic pressure bearing according to claim 5, wherein the radial bearing is made of ceramics. 8. A radial bearing, and a thrust bearing provided at one end of the radial bearing, and the radial bearing,
In a dynamic pressure bearing having a rotating body rotatably provided in the thrust bearing, a gap generated between the rotating body and the thrust bearing when the rotating body receives and rotates by the radial bearing and the thrust bearing. A dynamic pressure bearing, wherein a minimum value of the width is larger than a minimum value of a gap width generated between the radial bearing and the rotating body. 9. The dynamic pressure bearing according to claim 8, wherein, in the dynamic pressure bearing, a dynamic pressure generating groove is formed in both or at least one of the radial bearing and the thrust bearing. . 10. The hydrodynamic bearing according to claim 8, wherein when the rotating body comes into contact with the bearing, it comes into contact with a radial bearing having a low peripheral speed. 11. The dynamic pressure bearing according to claim 8, wherein the radial bearing is made of ceramics.