JPH08200353A - Dynamic pressure air bearing - Google Patents

Abstract

PURPOSE: To provide a dynamic pressure air bearing rotated smoothly by preventing the infiltration of the dust affecting the rotation into the dynamic pressure generating groove of the dynamic pressure air bearing from the outside. CONSTITUTION: This dynamic pressure air bearing is provided with a fixed section 34, a rotor 22 rotated adjacently to the fixed section 34, and a dynamic pressure generating groove 35A provided on the rotor 22 and/or the fixed section 34 and generating dynamic pressure. Air is engulfed by the rotation of the rotor 22, a gap is generated between the rotor 22 and the fixed section 34, and the dynamic pressure air bearing has a bearing function in the noncontact state. The maximum gap between the rotor 22 and the fixed section 34 at an air intake port is set smaller than the depth of the dynamic pressure generating groove 35A.

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 air bearing, and more specifically, a dynamic pressure generating groove is formed in a rotating body and / or a fixed portion, and the rotation of the rotating body causes the dynamic pressure generating groove to function. The present invention relates to a dynamic pressure type air bearing that generates a dynamic pressure to separate the elements in a thrust direction or a radial direction, and particularly smoothly rotates at a high speed.

[0002]

2. Description of the Related Art An air bearing is one which sends air between a rotating body and a fixed member to have a bearing function in a non-contact state, and there are static pressure type and dynamic pressure type. This dynamic pressure type air bearing is a system in which air is entrained by its rotation to generate buoyancy.

As this dynamic pressure type air bearing, for example, FIG. 10 is a sectional view showing a state before the operation of a conventional dynamic pressure type air bearing, and FIG. 11 shows a dynamic pressure generating groove in the conventional dynamic pressure type air bearing. FIG. 12 is a plan view showing an enlarged sectional view of a conventional dynamic pressure generating groove. As shown in the figure, a fixing member 3 having a fixing surface 31 is provided, and a plurality of dynamic pressure generating grooves 32 are formed in a spiral pattern on the fixing surface 31 gradually from the outer circumference to the vicinity of the central axis 1. . A rotating member 2 having a rotating surface 21 in a direction perpendicular to the fixed member 3 and the fixed central axis 1 is provided, and the rotating body 2 is rotated by the magnet M and the stator coil S about the central axis 1 of the fixed portion. . Due to the rotation of the rotary surface 21, air is entrained along the dynamic pressure generating groove 32 to generate buoyancy. More specifically, the rotating body 2 is smoothly rotated while levitating while forming a slight gap between the rotating surface 21 and the fixed surface 31. Examples of such a dynamic pressure type air bearing and manufacturing method are disclosed in JP-A-62-288719 and JP-A-63-
No. 57914 is disclosed.

[0004]

As shown in FIG. 12, a method for forming a dynamic pressure generating groove to float the rotating body 2 above the fixed member 3 and smoothly rotating the rotating body is disclosed in the large-scale disclosed. It is widely used from rotating devices to small rotating devices. The dynamic pressure generating groove is formed in a spiral pattern on the fixing surface 31 of the fixing member 3 gradually from the outer circumference toward the inner circumference, and the outside air is sucked from the outer peripheral surface of the dynamic pressure generating groove 32 by the rotation of the rotating body 2. Then, a dynamic pressure is applied to the rotating surface 21 to generate a levitation action. However, when the outside air is sucked from the outer peripheral surface of the dynamic pressure generating groove 32, the dust A contained in the outside air may be caught in the dynamic pressure groove 32. Dust is accumulated in the terminal portion 321 at the end of the dynamic pressure generating groove. Since the size of the dust A to be sucked is regulated by the flying height L and the groove depth L ₁ of the dynamic pressure generating groove 32, a large amount of dust is not entrained while the rotating body 2 is rotating, which is not a big problem.

However, when the rotation of the rotating body 2 is stopped in a state where the dust A is accumulated in the terminal portion 321, the rotating surface 21 and the dust A are in close contact with each other, and a large starting torque is required when restarting the rotating body 2. Becomes When the rotating body 2 is used to rotate a polygon mirror used in a small device such as a laser printer, a rotating motor 2 is started under the influence of dust A because a small high-speed motor with a low starting torque is generally used. The problem that can not occur occurs. Further, it has been found that when the image forming toner used in a laser printer or the like is scattered, the adhesion becomes remarkable due to the heat-specific coagulation property of the toner and the above-mentioned problem is likely to occur.

The object of the present invention is to solve at least one of the above problems.
In order to solve this problem, it is to provide a dynamic pressure type air bearing that prevents dust from entering the dynamic pressure generation groove of the dynamic pressure type air bearing that may affect rotation from the outside and allows smooth rotation. is there.

[0007]

The above object can be achieved by the following means. That is, (1) a fixed part, a rotating body that rotates adjacent to the fixed part, and the rotating body and / or
Or a dynamic pressure generating groove provided in the fixed portion for generating a dynamic pressure, and air is entrained by the rotation of the rotating body to generate a gap between the rotating body and the fixed portion to perform a bearing function in a non-contact state. In the dynamic pressure type air bearing, the dynamic pressure type air bearing is characterized in that the maximum gap between the rotating body of the air intake port and the fixed portion is smaller than the depth of the dynamic pressure generating groove. (1) The dynamic pressure type air bearing according to (1), characterized in that the pressure generating groove has a recessed pocket in part, and (3) the rotating body is provided with a polygon mirror. It is the dynamic pressure type air bearing described in (1).

Here, the fixed portion is a member fixed to the rotating body, for example, a central axis of the rotating body, a fixing member above and below the rotating body, and the like.

[0009]

An embodiment of the present invention will be described with reference to the drawings.
The fixing member of each of the examples has an outer diameter of, for example, about 20.
mm, but is not limited to this.

(Embodiment 1) A dynamic pressure type air bearing according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view (A) and a partially enlarged sectional view (B) of a dynamic pressure type air bearing according to the present invention in a rotation stopped state. The fixing member 34 forms a fixing surface 33, and a plurality of dynamic pressure generating grooves 35 are formed in a spiral pattern on the fixing surface 33 gradually from the outer circumference to the inner circumference (see FIG. 3). Further, the central axis 11 of the fixed portion and the fixed member 34 are fixed axes, and the rotating body 22 has a rotating surface 24. The rotating body 22 is a polygon mirror
222 is attached and rotates by the action of the magnet M and the stator coil S. When rotated, air is entrained to generate buoyancy and float as shown in FIG.

FIG. 2 is a partial sectional view of a floating dynamic pressure type air bearing according to the present invention. When the rotating body 22 rotates, air is drawn into the dynamic pressure generating groove 35 and the fixing surface of the fixing member 34.
The rotating surface 24 of the rotating body 22 floats by 33 with respect to 33.

FIG. 3 is a perspective view showing the dynamic pressure generating groove of the dynamic pressure type air bearing of the present invention. On the fixed surface 33, a plurality of dynamic pressure generating grooves 35 are formed in a spiral pattern gradually from the outer circumference toward the inner circumference.

Here, the dust prevention action of the dynamic pressure type air bearing will be described. By rotating the rotating body 22,
The dynamic pressure generating groove 35 having a spiral pattern entrains the air of the outside air and floats in the thrust direction. At this time, large dust A ₂ , fine dust A _1, etc. floating in the outside air are tried to be involved together. Large dust A ₂ is fixed to the groove 35 for dynamic pressure generation 3
It is blocked by the wall provided near the outer periphery of 4. Even if a minute dust A ₁ is sucked into the dynamic pressure generating groove 35, the rotating surface 24 does not come into contact with the dust A ₁ , so that a smooth start can be performed.

It can be easily understood that the dust prevention of the dynamic pressure type air bearing of the present invention is not limited to the thrust direction already described.

(Embodiment 2) A dynamic pressure type air bearing according to another embodiment of the present invention will be described with reference to the drawings. This embodiment is a modification of the first embodiment, in which the wall at the tip of the dynamic pressure generating groove is made low, and a small dust collecting pocket is provided at the end of the dynamic pressure generating groove.

FIG. 4 is an enlarged plan view (A) of a groove for generating dynamic pressure according to another embodiment of the present invention and a partial sectional view (B) of a dynamic pressure type air bearing. The same parts as those of the first embodiment are given only the reference numerals and the description thereof will be omitted. The fixing member 34 is provided with a dynamic pressure generating groove 35, the wall of width W provided at the tip of the dynamic pressure generating groove has a low height, and the pocket 35 of the end portion 351 of the dynamic pressure generating groove is formed.
2 is a concave groove. When the flying height is L, the groove depth of the dynamic pressure generating groove 35 is L ₁ , the groove depth of the pocket 352 is L ₂ , and the pocket width is L ₃ , L = 5 to 7 μm, L ₁ = 10 μm, L ₂ = 5
˜15 μm, L ₃ = 100 μm. Here the flying height L, and the groove depth of the tip of the dynamic pressure generating grooves and L _4, the height direction of the air inlet portion of the dynamic pressure generating grooves are L + L ₄ next, L ₄
When ≧ 0, L + L ₄ <L ₁ .

The dust prevention function of the dynamic pressure type air bearing will now be described.
And the large dust A ₂ is in the height direction L + of the air inlet.
L ₄ in is blocked so that the can not enter. When the minute dust A ₁ is inhaled, it is accumulated in the pocket 352 and the rotating surface is dust A ₁ when the rotating body 22 is started for a long time.
Since there is no contact with, it is possible to perform a smooth start.

(Embodiment 3) A dynamic pressure type air bearing according to another embodiment of the present invention will be described with reference to the drawings. This embodiment is a modification of the first embodiment, in which a small dust collecting pocket is provided at the end of the dynamic pressure generating groove.

FIG. 5 is an enlarged plan view (A) of a groove for dynamic pressure generation and a partial sectional view (B) of a dynamic pressure type air bearing according to another embodiment of the present invention. The same parts as those of the first embodiment are given only the reference numerals and the description thereof will be omitted. The fixing member 34 is provided with a dynamic pressure generating groove 35, and the wall height of the width W of the tip of the dynamic pressure generating groove is the fixed surface
Same as 33, pocket 352 at end 351 of groove for generating dynamic pressure
Has a concave groove. The groove depth of the dynamic pressure generating groove 35 is L ₁ ,
When the groove depth of the pocket 352 is L ₂ , the width is L ₃ , and the flying height is L, L ₁ = 10 μm, L ₂ = 5 to 15 μm, L ₃ = 100 μm, L
= 5 to 7 μm.

The dust prevention function of the dynamic pressure type air bearing will now be described.
And the large dust A ₂ is blocked by the L in the height direction of the air inlet so that it cannot enter. Further, when the minute dust A ₁ is sucked, it is accumulated in the pocket 352, and the rotating surface 24 does not come into contact with the dust A ₁ when the rotating body is activated for a long period of time, so that a smooth start can be performed.

(Embodiment 4) A dynamic pressure type air bearing according to another embodiment of the present invention will be described with reference to the drawings. This embodiment is a modification of the second embodiment, in which the wall at the tip of the dynamic pressure generating groove is made low, and a small dust collecting pocket is not provided at the end of the dynamic pressure generating groove.

FIG. 6 is an enlarged plan view (A) of a groove for dynamic pressure generation and a partial sectional view (B) of a dynamic pressure type air bearing according to another embodiment of the present invention. The same parts as those in the second embodiment are given only the reference numerals and the description thereof will be omitted. The fixed member 34 is provided with a dynamic pressure generating groove 35, and a groove having a width W (for example, 1 mm) at the tip of the dynamic pressure generating groove is a low groove 36, and the groove depth of the dynamic pressure generating groove 35 is L. ₁ = 10
μm. Here, the flying height is L, the groove depth at the tip is L ₄ ,
Assuming that the height direction of the air inlet is L + L ₄ , L ₄ ≧ 0, L
+ L ₄ <L ₁ .

The dust prevention function of the dynamic pressure type air bearing will now be described.
The large dust A ₂ is blocked by the height L + L ₄ of the air inlet so that it cannot enter. If a small amount of dust A ₁ is sucked in, the rotating body will be
Since the 4 does not come into contact with the dust A ₁ , a smooth start can be performed.

(Embodiment 5) A dynamic pressure type air bearing according to another embodiment of the present invention will be described with reference to the drawings. This embodiment is a modification of the third embodiment in which an arc portion is provided at the tip of the dynamic pressure generating groove.

FIG. 7 is an enlarged plan view (A) of a groove for dynamic pressure generation and a partial sectional view (B) of a dynamic pressure type air bearing according to another embodiment of the present invention. The same parts as those of the first embodiment are given only the reference numerals and the description thereof will be omitted. The fixed member 34 is provided with a dynamic pressure generating groove 35 having an arc R, and the pocket 352 of the terminal end 351 of the dynamic pressure generating groove has a concave groove. When the groove depth of the dynamic pressure generating groove 35 is L ₁ , the groove depth of the pocket 352 is L ₂ , the pocket width is L ₃ , and the flying height is L, L ₁ = 10 μm, L ₂ = 5 to 15 μ
m, L ₃ = 100 μm, L = 5 to 7 μm.

The dust prevention effect of the dynamic pressure type air bearing will now be described.
The large dust A ₂ is blocked by the floating amount L at the air inlet so that it cannot enter. Further, when a minute dust A ₁ is sucked, it is accumulated in the pocket 352 and the rotating surface 24 does not contact the dust A ₁ for a long period of time, so that a smooth start can be performed.

(Embodiment 6) A dynamic pressure type air bearing according to another embodiment of the present invention will be described with reference to the drawings.

FIG. 8 is an enlarged plan view (A) of a groove for dynamic pressure generation and a partial sectional view (B) of a dynamic pressure type air bearing according to another embodiment of the present invention. Grooves for dynamic pressure generation on the rotating surface 24 of the rotating body 22
23 are provided. The dynamic pressure generating groove 23 is formed by an arc R and a straight line portion from the position of W from the outer circumference of the rotating body 22. If the width is W and the groove depth is L ₅ , W = 1 mm, L ₅ = 10 μm,
L = 5 to 7 μm.

As a method of forming the dynamic pressure generating groove 35,
For example, it can be formed by etching or blasting in which alumina particles or the like are blown at high speed from the outside.

The dust prevention function of the dynamic pressure type air bearing will now be described.
And the large dust A ₂ is blocked by the height L of the air inlet so that it cannot enter.

(Embodiment 7) A dynamic pressure type air bearing according to another embodiment of the present invention will be described with reference to the drawings.

FIG. 9 is an enlarged plan view (A) showing a dynamic pressure generating groove of another embodiment of the present invention and a partial sectional view (B) of a dynamic pressure type air bearing. The fixing member 34 is provided with a dynamic pressure generating groove 35, and further, a pocket 352 is provided in the vicinity of the rotating shaft of the rotating body. On the other hand, a convex portion is provided on the outer periphery of the rotating body 22 as shown in the figure to form an air inlet portion between the rotating body 22 and the fixed member 34, and the floating amount is L, the groove depth is L ₁ , and the gap is Let L ₆ be L
₁ = 10 μm and L ₆ = 5-7 μm.

The dust prevention function of the dynamic pressure type air bearing will now be described.
The large dust A ₂ is blocked by the gap L ₆ at the air inlet so that it cannot enter. Even smaller dust A
_{If 1} is sucked in, it enters the groove 23 for dynamic pressure generation and pocket 3
It is accumulated in 52 and the rotating surface 24 does not come into contact with the dust A ₁ for a long period of time, so that a smooth start can be performed.

[0035]

With the above-mentioned structure, the following effects can be obtained.

According to the first aspect of the present invention, in the dynamic pressure type air bearing, even if the rotary member and / or the fixed member is provided with the dynamic pressure generating groove, dust is prevented from entering at the air inlet portion.
In addition, even if fine dust enters, it stays in the dynamic pressure generating portion of the dynamic pressure generating groove, and the dust does not have a bad effect. It can be used stably over a period of time.

According to the second aspect, in addition to the effect of the first aspect, even if fine dust enters into the dynamic pressure generating groove due to the entrainment of air, the dust will not reach a portion of the dynamic pressure generating groove. Collected in the formed pocket. Therefore, dust is not adversely affected, and particularly when the rotating body is started, it can be stably used for a long period of time even if a power source with a weak torque is used.

Further, according to the third aspect, in the dynamic pressure type air bearing having the polygon mirror in the rotating body, it is possible to prevent dust due to entrainment of air even when the polygon mirror is rotated at a high speed. Even when a power source with a weak torque is used, it can be stably used for a long period of time without adverse effects of dust, especially at the time of starting the rotating body. Also,
In a copying machine or the like using a polygon mirror, it is possible to prevent the influence of fine dust such as toner dust, cigarette tar, transfer paper dust, and house dust.

[Brief description of drawings]

FIG. 1 is a sectional view (A) and a partially enlarged sectional view (B) of a dynamic pressure type air bearing in a rotation stopped state of the present invention.

FIG. 2 is a partial cross-sectional view of a floating dynamic pressure type air bearing according to the present invention.

FIG. 3 is a perspective view showing a dynamic pressure generating groove of the dynamic pressure type air bearing of the present invention.

FIG. 4 is an enlarged plan view (A) of a groove for dynamic pressure generation and a partial sectional view (B) of a dynamic pressure type air bearing according to another embodiment of the present invention.

FIG. 5 is an enlarged plan view (A) of a dynamic pressure generating groove according to another embodiment of the present invention and a partial sectional view (B) of a dynamic pressure type air bearing.

FIG. 6 is an enlarged plan view (A) of a dynamic pressure generating groove of another embodiment of the present invention and a partial sectional view (B) of a dynamic pressure type air bearing.

FIG. 7 is an enlarged plan view (A) of a dynamic pressure generating groove according to another embodiment of the present invention and a partial sectional view (B) of a dynamic pressure type air bearing.

FIG. 8 is an enlarged plan view (A) of a dynamic pressure generating groove and a partial sectional view (B) of a dynamic pressure type air bearing according to another embodiment of the present invention.

FIG. 9 is an enlarged plan view (A) showing a dynamic pressure generating groove of another embodiment of the present invention and a partial sectional view (B) of a dynamic pressure type air bearing.
Is.

FIG. 10 is a cross-sectional view showing a state before operation of a conventional dynamic pressure type air bearing.

FIG. 11 is a plan view showing a groove for dynamic pressure generation in a conventional dynamic pressure type air bearing.

FIG. 12 is an enlarged sectional view showing a conventional dynamic pressure generating groove.

[Explanation of symbols]

1, 11 Central axis (fixed part) 2 Rotating body 21 Rotating surface 22 Rotating body 222 Polygon mirror 23 Dynamic pressure generating groove 24 Rotating surface 3 Fixing member 31 Fixing surface 32 Dynamic pressure generating groove 321 Terminal part 33 Fixed surface 34 Fixed Member 35, 35A Dynamic pressure generation groove 351 Terminal part 352 Pocket 36 groove A, A ₁ , A ₂ Dust L Flying height L ₁ , L ₂ , L ₄ , L ₅ Groove depth L ₃ Width L ₆ Gap S Stator coil M Magnet W Width R Arc

Claims (3)

[Claims] 1. A rotating body comprising: a fixed portion; a rotating body that rotates adjacent to the fixed portion; and a dynamic pressure generating groove that is provided in the rotating body and / or the fixed portion to generate a dynamic pressure. In the dynamic pressure type air bearing that has a bearing function in a non-contact state by generating air between the rotating body and the fixed portion by the rotation of, the maximum gap between the rotating body and the fixed portion of the air intake is A dynamic pressure type air bearing, which is smaller than the depth of the dynamic pressure generating groove. 2. The dynamic pressure type air bearing according to claim 1, wherein said dynamic pressure generating groove has a recess pocket in a part thereof. 3. The dynamic pressure type air bearing according to claim 1, wherein the rotating body is provided with a polygon mirror.