JP5770039B2 - Air dynamic pressure bearing and blower using the air dynamic pressure bearing - Google Patents

Description

  The present invention relates to an air dynamic pressure bearing used for a blower, an optical deflector, a color wheel motor, and the like, and a blower using the air dynamic pressure bearing.

A conventional air dynamic pressure bearing has a herringbone type dynamic pressure generating groove or a skew groove type dynamic pressure generating groove formed on a shaft or sleeve.
However, in the case where a herringbone type dynamic pressure generating groove is formed, the air that has entered from the outside in the axial direction of the groove is compressed at the flat part near the tip of the central part of the groove, and the pressure becomes high, and moisture in the air Condensation may occur, the condensed moisture stays there, the bearing load increases, the current increases, and in the worst case, the bearing is damaged by the shearing force of water.
Further, when the herringbone groove extends to the center portion, the pressure is increased only in the vicinity of the center portion of the groove, so that the state becomes a so-called cantilevered support, resulting in a drawback that the rotational stability is deteriorated.
Since the skew groove type dynamic pressure generating groove is formed, the bearing rigidity as in the herringbone groove type cannot be obtained, and the bearing rigidity is particularly low in the low speed rotation region (10 Kr / min). There has been a drawback that the shaft and the sleeve are in contact with each other at a relatively high number of rotations from the high speed rotation to the stoppage until the rotation is reached.

Japanese Patent Laid-Open No. 9-210052 JP-A-11-190329 JP 2000-92774 A JP 2001-304246 A

  In view of the above-mentioned conventional drawbacks, the present invention can provide sufficient bearing rigidity, and moisture caused by air condensation caused by compression in a herringbone type dynamic pressure generating groove can be used to remove moisture caused by straight type condensation prevention grooves. It is an object of the present invention to provide an air dynamic pressure bearing that can be efficiently removed and prevent the occurrence of defects caused by condensed moisture and a blower using the air 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 an air dynamic pressure bearing in which a herringbone type dynamic pressure generating groove is formed on a shaft or a sleeve, immediately after the pressure is increased by the herringbone type dynamic pressure generating groove. An air dynamic pressure bearing is constructed by forming at least one straight type dew condensation prevention groove that can be at atmospheric pressure or negative pressure near the rear in the traveling (rotating) direction from the portion where the dynamic pressure generating groove is formed. ing.
Further, the present invention provides a blower using an air dynamic pressure bearing in which a herringbone type dynamic pressure generating groove is formed on a shaft or a sleeve, and the atmospheric pressure immediately after the pressure is increased by the herringbone type dynamic pressure generating groove. Alternatively, a blower is configured by using an air dynamic pressure bearing in which at least one straight type dew condensation prevention groove capable of generating a negative pressure is formed near the rear in the traveling (rotating) direction from the portion where the dynamic pressure generating groove is formed. ing.

As is clear from the above description, the present invention has the following effects.
(1) According to claim 1, the pressure of the herringbone type dynamic pressure generating groove is increased, and at least one straight type dew condensation is formed on the side where the dynamic pressure generating groove is formed in the vicinity of the portion where air is likely to condense. Since the prevention groove is formed, the moisture due to condensation at the site where the pressure of the herringbone type dynamic pressure generation groove is increased is reduced by the condensation prevention groove, and the condensed moisture is sucked or the water vapor pressure is lowered. It is possible to remove condensation efficiently and prevent condensation.

  In addition, since the dew condensation prevention groove crosses the air (lubricating fluid), even if moisture is generated due to condensation, the moisture can be sucked into the condensation prevention groove and discharged.

Therefore, it is possible to prevent the occurrence of problems due to conventional condensation.
(2) The pressure of the herringbone type dynamic pressure generating groove is increased by the above (1), and at least one straight type of the dynamic type generating groove is formed on the side where the dynamic pressure generating groove is formed in the vicinity of the portion where air is likely to condense. Since it is only necessary to form the anti-condensation groove, the structure is easy and it can be manufactured at low cost.
(3) According to the above (1), the pressure increased by the herringbone type dynamic pressure generating groove is hardly lowered, so that the original bearing rigidity of the herringbone type dynamic pressure generating groove can be obtained.
(4) Claim 2 can also obtain the same effect as said (1)-(3).
(5) Claim 3 can also obtain the same effect as the above (1) to (3), and can obtain a blower that does not cause a problem of influence due to condensed moisture while maintaining bearing rigidity.

The top view of the use condition of the 1st form for implementing this invention. The expanded sectional view which follows the 2-2 line of FIG. Explanatory drawing of the 1st Embodiment of this invention. The expanded view of the shaft of the 1st Embodiment of this invention. Sectional drawing of the sleeve of the 1st Embodiment of this invention. The top view of the impeller of the 1st Embodiment of this invention. Explanatory drawing which shows the groove depth and pressure distribution of the AA line part of FIG. Explanatory drawing which shows the groove depth and pressure distribution of the BB line part of FIG. Explanatory drawing which shows the three-dimensional model of the pressure distribution of FIG. The longitudinal cross-sectional view of the 2nd form for implementing this invention. Explanatory drawing of the air dynamic pressure bearing of the 2nd form for implementing this invention. The expanded view of the sleeve of the 2nd form for implementing this invention. The longitudinal cross-sectional view of the 3rd form for implementing this invention. Explanatory drawing of the air dynamic pressure bearing of the 3rd form for implementing this invention. The expanded view of the shaft of the 3rd form for carrying out the present invention. The longitudinal cross-sectional view of the 4th form for implementing this invention. Explanatory drawing of the air dynamic pressure bearing of the 4th form for implementing this invention. The expanded view of the shaft of the 4th form for implementing this invention. The longitudinal cross-sectional view of the 5th form for implementing this invention. Explanatory drawing of the air dynamic pressure bearing of the 5th form for implementing this invention. The expanded view of the shaft of the 5th form for implementing this invention. The longitudinal cross-sectional view of the 6th form for implementing this invention. Explanatory drawing of the air dynamic pressure bearing of the 6th form for implementing this invention. The expanded view of the shaft of the 6th form for implementing this invention. FIG. 25 is an explanatory diagram showing a groove depth and a pressure distribution at the line AA in FIG. The longitudinal cross-sectional view of the 7th form for implementing this invention. Explanatory drawing of the air dynamic pressure bearing of the 7th form for implementing this invention. The expanded view of the shaft of the 7th form for implementing this invention.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.

  In the first embodiment for carrying out the present invention shown in FIGS. 1 to 9, reference numeral 1 denotes a blower using an air dynamic pressure bearing 2 of the present invention. The blower 1 is formed by an air suction port 3 and a discharge port 4. Of the motor 6 using the case body 5, the motor 6 using the air dynamic pressure bearing 2 attached to the case body 5 and driven at high speed rotation, and the motor 6 so as to be positioned on the outer periphery of the motor 6. It is comprised with the impeller 7 fixed to the rotation member which can attract | suck air from the air suction port 3 of the said case body 5 by rotation, and can discharge | emit it from the said discharge port 4.

  As shown in FIGS. 1 to 3, the case body 5 covers a base plate 8 and an outer peripheral portion of the motor 6 and a lower portion of the impeller 7 fixed on the base plate 8 with a plurality of screws 9. A lower case 10, an air suction port 3 is formed at the center of the upper surface fixed with a plurality of screws 11 at the upper part of the lower case 10, and an upper case 12 covering the upper part of the impeller 7, and the upper case 12 And a discharge port 4 formed on the outer peripheral portion of the lower case 10.

  As shown in FIGS. 3 to 5, the motor 6 includes a substrate 13 provided with a motor drive circuit (not shown) fixed to the upper surface of the base plate 8 of the case body 5, and the substrate 13 above the substrate 13. An air dynamic pressure bearing 2 including a shaft 14 fixed so as to protrude, and a sleeve 16 disposed on the outer peripheral portion of the shaft 14 via a minute gap 15, and the outer peripheral portion of the sleeve 16 of the air dynamic pressure bearing 2 The back yoke 17 attached to the substrate 13, the coreless corrugated continuous coil 18 attached to the substrate 13 so as to be located on the outer periphery of the back yoke 17, and the outer periphery of the coreless corrugated continuous coil 18 The rotor 19 provided with the provided permanent magnets, the sleeve 16, the back yoke 17 and the rotor 19 are supported, and the upper portion of the shaft 14 and the rotor 19 are supported. A ring-shaped thrust magnet 22 fixed to a recess 21 at the top of the hub 20 covering the shaft 14, and a thrust member 22 so as to face the thrust magnet 22. The ring-shaped thrust magnet 23 is fixed to the upper portion of the shaft 14.

  As shown in FIGS. 4 and 5, the air dynamic pressure bearing 2 has three pairs of herringbone type dynamic pressure generating grooves 24 formed at the upper and lower positions of the shaft 14 and divided into three equal parts with respect to the outer periphery. , 24, 24 and three of these three pairs of herringbone type dynamic pressure generating grooves 24, 24, 24 formed in parallel with the axial direction in the vicinity of a portion (flat portion) where air is likely to condense Straight type condensation prevention grooves 25, 25, 25.

  As shown in FIGS. 2 and 6, the impeller 7 is fitted to and fixed to a boss portion of a hub 20 as a rotating member of the motor 6, and outward from a lower outer peripheral portion of the inlay 26 portion. A bottom plate 27 that is integrally molded so as to protrude, and a plurality of long blades in an arc shape that are integrally molded on the bottom plate 27 at a predetermined interval so that the height dimension sequentially decreases outward and downward from the inlay 26 portion. 28 and a plurality of long blades 28, 28, the starting point of which is provided closer to the outer peripheral portion than the long blades 28, and a large number of arcs formed in the same height and arc as the long blades 28. A short blade 29 and a bottom surface near the central portion of the bottom plate 27, each opening between the long blade 28 and the short blade 29, the discharge port side of the case body 5 of the long blade 28 and the short blade 29; Different from the anti-discharge side It is composed of a ring-shaped pressure equalization space 30 serving as the axis and coaxial the impeller 7 to prevent the applied pressure.

  When the blower 1 configured as described above is driven, the impeller 7 rotates at high speed, and air is sucked into the impeller chamber 31 of the upper case 12 and the lower case 10 from the air suction port 3 of the case body 5, and the pressure is increased and discharged. Discharge from outlet 4. For this reason, even if it is small, it can blow high pressure with a large air volume.

  In addition, the air dynamic pressure bearing 2 of the motor 6 generates pressure (dynamic pressure) by three pairs of herringbone type dynamic pressure generating grooves 24, 24, 24, and holds the bearings. Even if the water vapor pressure of the air in the vicinity of the portion where the pressure is increased by the dynamic pressure generating grooves 24, 24, 24 exceeds the saturated water vapor pressure and condensation occurs, the herringbone type dynamic pressure generating grooves 24, 24 In order to prevent the pressure increased at 24 from dropping, straight type dew condensation prevention grooves 25, 25 provided slightly behind from the location where the maximum pressure is generated, slightly in the traveling (rotating) direction, By reducing the pressure by 25 and sucking condensed moisture or lowering the water vapor pressure, moisture due to condensation can be removed, and the original bearing of the herringbone type dynamic pressure generating groove Stiffness can be obtained.

For this reason, stable rotation is possible from a low-speed rotation region of about 10,000 rotations per minute to a high-speed rotation region of about 100,000 rotations, and problems due to condensation can be prevented.
Here, the shearing force in the case where moisture is generated by dew condensation in the air (lubricating fluid) under certain conditions and the shearing force in the case where moisture does not occur will be described.
Bearing clearance: 3 μm, shaft diameter: φ8 mm, rotation speed: 300,000 revolutions per minute,
The shearing force of air and the shearing force of water can be obtained by the following equations.
Shear force τ = μ · v / Cr
= Μ ・ r ・ ω / Cr
= 2πμ · r · N · / 60Cr (N / m ^ 2)
(However, ^ represents the factorial.)
μ: Viscosity (Pa · S)
v: Bearing peripheral speed (m / sec)
Cr: Bearing clearance (radial clearance) (m)
r: Bearing radius (m)
ω: Bearing rotation speed (rad / sec)
N: Bearing rotation speed (r / min)
When calculating by adding the viscosity of air (numerical value 1) and the viscosity of water (numerical value 2) to the above formula,
Shear force of air: 80 N / square meter Water shear force: 4,226 N / square meter
Condensation of air occurs when air (lubricating fluid) is compressed by the dynamic pressure generation groove, and the pressure in the flat part near the tip of the center part of the groove (the tip part inside the shaft) increases. When this pressure exceeds the saturated water vapor pressure, Air condenses and liquefies moisture.
The water shear force is generated when the bearing gap (between the shaft and the sleeve) is narrow and water crosses between them, in addition to the speed difference between the shaft and the sleeve. It is believed that there is.
For this reason, even if moisture liquefies due to condensation, it is unlikely that such shearing force will immediately occur, but by continuing high-speed rotation, the bearing gap is filled with water and suddenly damages the bearing. It becomes.
The condensation prevention groove of the present invention is at atmospheric pressure or negative pressure during rotation, and even if the pressure is increased by the herringbone type dynamic pressure generation groove and condensation occurs in the air,
Immediately after that, the pressure drops due to the anti-condensation groove, and the condensed moisture is sucked with it.
Or since the water vapor pressure of air can be reduced, the water | moisture content by dew condensation can be removed.
In addition, since the condensation prevention groove always crosses the air (lubricating fluid), even if moisture is generated due to condensation, the moisture can be sucked into the condensation prevention groove and discharged.
As described above, the air dynamic pressure bearing of the present invention has the effect of lowering the water vapor pressure so that condensation itself does not occur and the two effects of immediately sucking and discharging the moisture into the condensation prevention groove even if condensation occurs. The shearing force of water does not act on the bearing gap.
In order to prevent the pressure increased by the herringbone type dynamic pressure generating groove from dropping, the direction of travel (rotation) is slightly rearward from the location where the maximum pressure is generated (flat part). Since the straight type anti-condensation groove is provided, the inherent bearing rigidity of the herringbone type dynamic pressure generating groove can be obtained.
(Different forms for carrying out the invention)
Next, different modes for carrying out the present invention shown in FIGS. 10 to 28 will be described. In the description of the different embodiments for carrying out the present invention, the same components as those in the first embodiment for carrying out the present invention are denoted by the same reference numerals, and redundant description is omitted.

  The second embodiment for carrying out the present invention shown in FIGS. 10 to 12 is mainly different from the first embodiment for carrying out the present invention in an air dynamic pressure bearing 2A, which is the air dynamic pressure bearing. In 2A, three pairs of herringbone type dynamic pressure generating grooves 24, 24, 24 and straight type condensation prevention grooves 25, 25, 25 are formed in the sleeve 16, and a shaft 14A having no grooves on the outer peripheral portion is used. Thus, even with the blower 1A using the air dynamic pressure bearing 2A formed as described above, the same effects as the first embodiment for carrying out the present invention can be obtained, and the dew condensation preventing grooves 25, 25, 25 is formed on the inner peripheral portion of the sleeve 16, and the rotation of the sleeve 16 causes the centrifugal force to act on the air (lubricating fluid), thereby more reliably preventing the occurrence of problems due to condensed moisture. It can be.

  The third embodiment for carrying out the present invention shown in FIGS. 13 to 15 is mainly different from the first embodiment for carrying out the present invention in an air dynamic pressure bearing 2B, which is the air dynamic pressure bearing. 2B has three pairs of herringbone type dynamic pressure generating grooves 24A, 24A, 24A of different lengths formed on the upper and lower portions of the shaft 14. Even in the blower 1B using the air dynamic pressure bearing 2B in which three pairs of herringbone type dynamic pressure generating grooves 24A, 24A and 24A are formed on the shaft 14 as described above, the first embodiment for carrying out the present invention is used. The same effect as that of the embodiment can be obtained, and even when different bearing rigidity is required between the upper and lower sides of the shaft 14, it can be easily handled.

  The fourth embodiment for carrying out the present invention shown in FIGS. 16 to 18 is mainly different from the first embodiment for carrying out the present invention in an air dynamic pressure bearing 2C, and this air dynamic pressure bearing. 2C has three pairs of arcuate herringbone type dynamic pressure generating grooves 24B, 24B, 24B formed in the shaft 14. Even in the blower 1C using the air dynamic pressure bearing 2C in which three pairs of herringbone type dynamic pressure generating grooves 24B, 24B and 24B are formed on the shaft 14 as described above, the first embodiment for carrying out the present invention is used. The same effect as the form can be obtained.

  The fifth embodiment for carrying out the present invention shown in FIGS. 19 to 21 is mainly different from the first embodiment for carrying out the present invention in an air dynamic pressure bearing 2D, which is the air dynamic pressure bearing. 2D is a straight type dew condensation prevention groove 25A, 25A, 25A that does not communicate with the three pairs of herringbone type dynamic pressure generating grooves 24, 24, 24 on the shaft 14; It forms so that it may overlap with the inner edge part of the groove | channels 24, 24, 24 in an axial direction. A blower 1D using an air dynamic pressure bearing 2D in which straight type dew condensation preventing grooves 25A, 25A, 25A that do not communicate with the three pairs of herringbone type dynamic pressure generating grooves 24, 24, 24 are formed on the shaft 14 as described above. Also, the same effect as the first embodiment for carrying out the present invention can be obtained.

  The inner end portions of the dynamic pressure generating grooves 24, 24, 24 and the end portions of the condensation prevention grooves 25A, 25A, 25A may be formed on the same peripheral surface (overlap length = 0 mm).

  In the sixth embodiment for carrying out the present invention shown in FIGS. 22 to 25, the main difference from the third embodiment for carrying out the present invention is an air dynamic pressure bearing 2E, which is the air dynamic pressure bearing. 2E forms straight type dew condensation prevention grooves 25B, 25B, 25B in a state where the shaft 14 is inclined with respect to the axial direction. Even in the blower 1E using the air dynamic pressure bearing 2E in which the straight type dew condensation preventing grooves 25B, 25B, and 25B having such an inclination on the shaft 14 are formed, it is the same as the third embodiment for carrying out the present invention. Effects can be obtained.

  In the seventh embodiment for carrying out the present invention shown in FIGS. 26 to 28, the main difference from the first embodiment for carrying out the present invention is an air dynamic pressure bearing 2F. 2F forms one straight type dew condensation prevention groove 25 in the shaft 14. Even in the blower 1F using the air dynamic pressure bearing 2F in which one straight type dew condensation prevention groove 25 is formed on the shaft 14 as described above, the same effects as the first embodiment for carrying out the present invention are obtained. can get.

  In addition, although the air blower was demonstrated in embodiment which implements this invention, this invention is not restricted to this, It can be used as air dynamic pressure bearings, such as optical deflectors other than an air blower, and a color wheel motor.

In the embodiment for carrying out the present invention, the air dynamic pressure bearing has been described in which the herringbone type dynamic pressure generating groove is formed in a portion equally divided into three with respect to the outer periphery of the shaft. Not limited to this, a herringbone type dynamic pressure generating groove of three or more equal portions may be formed on the outer peripheral portion of the shaft.
In addition, even if the sleeves are formed with three pairs of herringbone type dynamic pressure generating grooves and straight type dew condensation preventing grooves according to the third, fourth, fifth, sixth and seventh embodiments, the same effect is obtained. can get.
Further, the skew groove straight type dew condensation preventing groove may not be a perfect straight shape, such as being formed in an arc shape like the three pairs of herringbone type dynamic pressure generating grooves of the fourth embodiment.

  The present invention is used in an industry for manufacturing an air dynamic pressure bearing and a blower using the air dynamic pressure bearing.

1, 1A, 1B, 1C, 1D, 1E, 1F: blower,
2, 2A, 2B, 2C, 2D, 2E, 2F: air dynamic pressure bearing,
3: Air suction port, 4: Discharge port,
5: Case body, 6: Motor,
7: Impeller, 8: Base plate,
9: Screw, 10: Lower case,
11: Screw, 12: Upper case,
13: Substrate, 14, 14A: Shaft
15: Micro gap 16: Sleeve
17: Back yoke, 18: Coreless waveform continuous coil,
19: Rotor, 20: Hub,
21: recess, 22: thrust magnet,
23: Thrust magnet,
24, 24A, 24B: Herringbone type dynamic pressure generating grooves,
25, 25A, 25B: Straight type condensation prevention groove,
26: Inlay, 27: Bottom plate,
28: Long feather, 29: Short feather,
30: Pressure uniform space, 31: Impeller chamber.

Claims (3)

In an air dynamic pressure bearing in which a herringbone type dynamic pressure generating groove is formed on a shaft or a sleeve, at least one bearing that can be brought to atmospheric pressure or negative pressure immediately after the pressure is increased by the herringbone type dynamic pressure generating groove. An air dynamic pressure bearing characterized in that the above-described straight type dew condensation prevention groove is formed near the rear in the traveling (rotating) direction from the portion where the dynamic pressure generating groove is formed . 2. The air dynamic pressure bearing according to claim 1, wherein the straight type dew condensation preventing groove is formed in a state parallel to the axial direction or inclined with respect to the axial direction. In a blower using an air dynamic pressure bearing in which a herringbone type dynamic pressure generating groove is formed on a shaft or a sleeve, the herringbone type dynamic pressure generating groove can make atmospheric pressure or negative pressure immediately after the pressure is increased. A blower using an air dynamic pressure bearing in which at least one straight type dew condensation prevention groove is formed near the rear in the traveling (rotating) direction from a portion where the dynamic pressure generating groove is formed .

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