JP2007057048A - Fluid dynamic pressure bearing and motor comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid dynamic pressure bearing and a motor comprising the fluid dynamic pressure bearing capable of stably rotating at high speed, having high durability, reducing noise and efficiently preventing clogging and galling of a dynamic pressure generating portion. <P>SOLUTION: This fluid dynamic pressure bearing is composed of the dynamic pressure generating portion disposed on a shaft or a bearing, a stability keeping recessed portion positioned on an outer end portion at an opening side of the dynamic pressure generating portion, and formed as a clearance larger than a bearing clearance formed on the shaft or the bearing, and a dust intrusion preventing portion formed at an outer part of the stability keeping recessed portion as a clearance approximately same as the bearing clearance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic fluid bearing used for an optical deflector used in a low noise information device, an imaging device, a measuring device and the like having excellent durability with high speed rotation, and a motor including the hydrodynamic pressure bearing.

  In the conventional fluid dynamic pressure bearing, the bearing is disposed so that the outer end portion of the dynamic pressure generating portion is the outer end portion of the outer periphery of the shaft on which the dynamic pressure generating portion is formed.

Therefore, stable high-speed rotation is possible, but due to the flow of fluid from the outside to the inside of the dynamic pressure generating part, it is larger than the clearance of the bearing, and the depth of the groove of the dynamic pressure generating part is added to the clearance. There was a drawback that dust smaller than the one entered the dynamic pressure generating part, resulting in clogging and stagnation.
JP 2000-347122 A

  In view of the conventional drawbacks as described above, the present invention is capable of stable high-speed rotation, excellent durability, and low noise, and can efficiently prevent clogging and galling of the dynamic pressure generating portion. An object of the present invention is to provide a motor including a dynamic pressure bearing and a fluid dynamic pressure bearing.

The above and other objects and novel features of the present invention will become more fully apparent when the following description is read in conjunction with the accompanying drawings.
However, the drawings are for explanation only and do not limit the technical scope of the present invention.

In order to achieve the above object, the present invention provides a dynamic pressure generating portion formed on one of a shaft and a bearing, and either the shaft or the bearing positioned at an outer end portion on the open side of the dynamic pressure generating portion. A stability holding recess formed to be larger than the bearing clearance formed on one of the bearings, and a dust intrusion prevention portion formed in an outer portion of the stability holding recess and having substantially the same clearance as the bearing clearance. It constitutes a fluid dynamic pressure bearing.

  The present invention relates to a motor including a fluid dynamic pressure bearing, and includes a dynamic pressure generating portion formed on one of the shaft and the bearing of the fluid dynamic pressure bearing of the motor and an outer end portion on the open side of the dynamic pressure generating portion. The stability holding recess formed so as to be larger than the bearing clearance formed in either the shaft or the bearing, and the bearing clearance formed in the outer portion of the stability holding recess. A motor including a fluid dynamic pressure bearing is configured with the dust intrusion prevention portion in the gap.

  As is clear from the above description, the present invention has the following effects.

(1) A dynamic pressure generating portion formed on one of the shaft and the bearing, and a bearing gap formed on either the shaft or the bearing, which is located at the outer end portion on the open side of the dynamic pressure generating portion. Because it is composed of a stability holding recess formed to have a larger gap and a dust intrusion prevention portion that is almost the same gap as the bearing gap formed on the outer portion of the stability holding recess, it prevents dust entry. It is possible to prevent the entry of dust larger than the bearing gap into the dynamic pressure generating portion.
Therefore, it is possible to efficiently prevent the problem that galling occurs due to the intrusion of dust larger than the bearing gap as in the prior art.

(2) Even if the dust intrusion preventing portion is formed by the stability retaining recess of (1), stable high-speed rotation can be achieved without generating a whirl as in the prior art.
Therefore, a fluid dynamic pressure bearing having excellent durability and low noise can be obtained.

(3) Since the stability holding recess and the dust intrusion prevention unit need only be formed according to (1), the structure is simple and can be implemented easily.

(4) In claim 2, the same effects as in the above (1) to (3) can be obtained.

(5) According to the third aspect, the same effects as the above (1) to (3) can be obtained, and stability of high speed rotation and entry of dust can be prevented in an optimum state.

(6) In the fourth and fifth aspects, the same effects as in the above (1) to (3) can be obtained.

  Hereinafter, the present invention will be described in detail from the best mode for carrying out the present invention shown in the drawings.

  In the best mode for carrying out the present invention shown in FIGS. 1 to 7, reference numeral 1 denotes a motor having a fluid dynamic pressure bearing according to the present invention. The motor 1 has a plurality of mounting screws on its outer periphery. A base plate 3 in which insertion holes 2, 2, 2 are formed, a shaft 4 fixed so as to protrude upward from a substantially central portion of the base plate 3, and both ends of the shaft 4 except for both ends. Dynamic pressure generating portions 6 and 6 having a large number of dynamic pressure generating grooves 5 and 5 of any one of herringbone type, step type, skew type, etc. formed in the part, and dynamic pressure on the outer peripheral portion of the shaft 4 A rotatable sleeve 9 having both ends positioned at both ends of the shaft 4 and serving as dust entry preventing portions 8 and 8 through a bearing gap 7 capable of generating The inner end portion of the dynamic pressure generating portion 6, 6 on the outer end portion A rotor-shaped stability retaining recess 10, 10 larger than the bearing gap 7 formed to be positioned, a rotor 11 on which a permanent magnet attached to the outer periphery of the sleeve 9 is disposed, and the rotor 11 In the embodiment of the present invention, such as a single winding, a double winding, a triple winding, and the like, which are fixedly attached to the base plate 3 so as to be positioned on the outer peripheral portion, a cylindrical coreless corrugated continuous coil 12 having a triple winding is provided. A back yoke 13 provided on the outer periphery of the coreless corrugated continuous coil 12, a hub 14 that supports the back yoke 13 and the sleeve 9 and the rotor 11 in a fixed state, and the hub 14 or The back yoke 13, in the embodiment of the present invention, attached to the back yoke 13 by a cover 15 and a holder 16, and perpendicular to the axial direction of the shaft 4. A collar wheel 17 protruding outward, a ring-shaped thrust magnet 19 fixed to the recess 18 at the top of the hub 14, and a function as a vertical stopper that is attracted to the inner side of the thrust magnet 19. The thrust magnet 20 is fixed to the upper portion of the shaft 4.

In the fluid dynamic pressure bearing of the motor 1 configured as described above, both end portions of the sleeve 9 and both end portions of the shaft 4 are dust intrusion preventing portions 8 and 8 having the same clearance as the bearing clearance 7 as shown in FIG. As in the prior art, dust having a size larger than the bearing gap 7 and having a size plus the depth of the dynamic pressure generating grooves 5 and 5 does not enter the bearing gap 7, and galling due to the entry of the dust can be efficiently prevented.
In addition, as shown in the locus of eccentricity and eccentric angle in the translation mode shown in FIG. 4, the translation locus of the last one rotation shown in FIG. 5, and the translation locus of the last two rotations shown in FIG. The recesses 10 and 10 do not reduce the stability of the bearing, and the arrangement of the rotor 11 and the coreless corrugated continuous coil 12 in which a permanent magnet having a rotating structure is arranged on the outer periphery of the sleeve 9 generates a magnetic force. There is no harmful force applied to the shaft 4 and the sleeve 9 from the circuit, and smooth rotation at high speed is possible.
[Different forms for carrying out the invention]

  Next, different modes for carrying out the present invention shown in FIGS. 8 to 19 will be described. In the description of these different modes for carrying out the present invention, the same components as those in the best mode for carrying out the present invention are designated by the same reference numerals and redundant description is omitted. To do.

  The second embodiment for carrying out the present invention shown in FIGS. 8 to 10 is mainly different from the best first embodiment for carrying out the present invention in that the outer sides of the dynamic pressure generating sections 6 and 6 are the same. A fluid constituted by using the shaft 4A and the sleeve 9A in that the shaft 4A in which the ring-shaped stability holding recesses 10 and 10 are formed at the end and the sleeve 9A in which only the bearing hole 21 is formed are used. Even in the case of the motor 1A provided with the hydrodynamic bearing, the same operational effects as those of the best first embodiment for carrying out the present invention can be obtained.

  The third embodiment for carrying out the present invention shown in FIGS. 11 to 13 is mainly different from the best first embodiment for carrying out the present invention inside the stability holding recesses 10 and 10. In terms of using a sleeve 9B formed with dynamic pressure generating portions 6A, 6A having a large number of dynamic pressure generating grooves 5A, 5A inside the end portion, and a shaft 4B that is not formed on the outer peripheral portion, Even in the motor 1B including the fluid dynamic pressure bearing configured by using such a sleeve 9B and the shaft 4B, the same operational effects as those of the best first embodiment for carrying out the present invention can be obtained.

  The fourth embodiment for carrying out the present invention shown in FIGS. 14 to 16 is mainly different from the third embodiment for carrying out the present invention in that the ring-shaped stability holding recesses 10 and 10 are formed. Since the sleeve 9C formed only on the dynamic pressure generating portions 6A and 6A is used on the shaft 4C side, the motor 1C including the fluid dynamic pressure bearing configured using the shaft 4C and the sleeve 9C is used. The same effects as those of the third embodiment for carrying out the present invention can be obtained.

The fifth embodiment for carrying out the present invention shown in FIGS. 17 to 19 is mainly different from the best first embodiment for carrying out the present invention in that dynamic pressure is applied to the shaft 4D on the opening end side. The shaft 4D, the sleeve 9D and the shaft 4D configured as described above are formed in that the generating portion 6 is formed, the ring-shaped stability holding recess 10 is formed in the corresponding portion of the sleeve 9D, and the hub 14A having no opening is used in the upper portion. Even in the motor 1D including the fluid dynamic pressure bearing configured using the hub 14A, the same effects as those of the best first embodiment for carrying out the present invention can be obtained.
The embodiment for carrying out the present invention can be similarly applied to the second, third and fourth embodiments for carrying out the present invention.

In the embodiments for carrying out the present invention, the shafts 4, 4 </ b> A, 4 </ b> B, 4 </ b> C, and 4 </ b> D have been described. However, the present invention is not limited thereto, and the sleeves 9, 9 </ b> A, 9 </ b> B, 9 </ b> C, Similar effects can be obtained by fixing the shaft 9D and rotating the shafts 4, 4A, 4B, 4C, and 4D.
Moreover, although each form which implements this invention demonstrated what uses a coreless waveform continuous coil as a coil, this invention is not restricted to this, You may use a coil other than this.

  The present invention is used in the industry of manufacturing a fluid dynamic pressure bearing and a motor including the fluid dynamic pressure bearing.

The top view of the best 1st form for implementing this invention. Sectional drawing which follows the 2-2 line of FIG. BRIEF DESCRIPTION OF THE DRAWINGS The principal part explanatory drawing of the best 1st form for implementing this invention. The figure which shows the locus | trajectory of eccentricity rate and eccentric angle of translation mode. Explanatory drawing of the translation locus of one last rotation. Explanatory drawing of the translation locus of the last 2 rotations. Explanatory drawing of the state which prevents intrusion of garbage. The top view of the 2nd form for carrying out the present invention. Sectional drawing which follows the 9-9 line of FIG. Explanatory drawing of the principal part of the 2nd form for implementing this invention. The top view of the 3rd form for carrying out the present invention. Sectional drawing which follows the 12-12 line of FIG. Explanatory drawing of the principal part of the 3rd form for implementing this invention. The top view of the 4th form for carrying out the present invention. FIG. 15 is a sectional view taken along line 15-15 in FIG. 14; Explanatory drawing of the principal part of the 4th form for implementing this invention. The top view of the 5th form for implementing this invention. FIG. 18 is a sectional view taken along line 18-18 in FIG. 17; Explanatory drawing of the principal part of the 5th form for implementing this invention.

Explanation of symbols

1, 1A, 1B, 1C, 1D: a motor provided with a fluid dynamic pressure bearing,
2: Screw insertion hole 3: Base plate
4, 4A, 4B, 4C, 4D: shaft,
5, 5A: dynamic pressure generating groove, 6: dynamic pressure generating portion,
7: Bearing clearance, 8: Dust entry prevention part,
9, 9A, 9B, 9C, 9D: Sleeve,
10: Stability retaining recess 11: Rotor
12: Coreless waveform continuous coil, 13: Back yoke,
14, 14A: Hub, 15: Cover,
16: Holder, 17: Color wheel,
18: recess, 19: thrust magnet,
20: Thrust magnet, 21: Bearing hole.

Claims (5)

A dynamic pressure generating portion formed on one of the shaft and the bearing, and a gap larger than a bearing clearance formed on either the shaft or the bearing, which is located at the outer end portion on the open side of the dynamic pressure generating portion. A fluid dynamic pressure bearing comprising: a stability holding recess formed so as to be; and a dust intrusion prevention portion having substantially the same clearance as the bearing gap formed in an outer portion of the stability holding recess. A dynamic pressure generating portion formed in one of the shaft and the bearing, and a clearance larger than a bearing clearance formed in either one of the shaft or the bearing, located at both outer ends of the dynamic pressure generating portion. And a dust-like intrusion prevention portion formed at both outer portions of the stability holding concave portion and having a clearance substantially the same as the bearing gap. Pressure bearing. 3. The fluid dynamic pressure bearing according to claim 1, wherein an inner end portion of the stability holding recess is formed on the same plane as an outer end portion of the dynamic pressure generating portion. In a motor including a fluid dynamic pressure bearing, a dynamic pressure generating portion formed on either the shaft or the bearing of the fluid dynamic pressure bearing of the motor, and an outer end portion on the open side of the dynamic pressure generating portion, Stability retaining recess formed to be larger than the bearing clearance formed on either the shaft or the bearing, and dust having substantially the same clearance as the bearing clearance formed on the outer portion of the stability retaining recess. A motor comprising a fluid dynamic pressure bearing comprising an intrusion prevention unit. In a motor provided with a fluid dynamic pressure bearing, the shaft is located at either one of the shaft of the fluid dynamic pressure bearing of the motor or the bearing, and at both outer ends of the dynamic pressure generation portion. Alternatively, a ring-shaped stability holding recess formed to be larger than the bearing clearance formed in one of the bearings, and the bearing clearance formed on both outer portions of the stability holding recess. A motor provided with a fluid dynamic pressure bearing, characterized by comprising a dust intrusion prevention unit in the same gap.

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