JP2004183733A - Fluid bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in a conventional fluid bearing that as the inclination unexpected in design, is generated in a sleeve hollow part because of the variation in manufacturing, a thrust bearing flying height differs from a design value, whereby the rubbing may occur in the thrust direction when the flying height is smaller than the design value, and the thrust bearing may over-fly when the flying height is larger than the design value. <P>SOLUTION: Bearing lengths of an upper bearing and a lower bearing of a radial bearing are determined in accordance with the inclination direction of a sleeve (a bearing length is short at a narrow hollow part, and a bearing length is long at a wide hollow part), whereby the rubbing in the thrust direction, and the over-flying of the thrust bearing can be prevented. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fluid bearing used for a hard disk drive and the like.
[0002]
[Prior art]
Hereinafter, an example of a conventional hydrodynamic bearing device will be described with reference to FIG. 5 or FIG. FIG. 5 or FIG. 6 is a sectional view of a conventional hydrodynamic bearing device. In FIG. 5 or FIG. 6, reference numeral 1 denotes a shaft, which is rotatably fitted together with the sleeve 2. A thrust plate 3 is in contact with the end face 1 </ b> A of the shaft 1 and is fixed to an end of the sleeve 2. The thrust plate 3 is provided with a pressure generating groove 3A, into which a lubricant 4 is injected to constitute a thrust bearing. Pressure generating grooves 2A, 2B are provided on the inner circumference of the sleeve 2 or the outer circumference of the shaft 1, and a lubricant 4 is injected to form a radial bearing. Two or more radial bearings are provided, and the length of the upper bearing 5 above the radial bearing is shorter on the lower side than on the upper side, and the lower bearing 6 below the radial bearing is on the upper side from the lower side. Is short. On the other hand, the shape of the hollow portion of the sleeve 2 has no inclination in design, but due to variations in actual manufacture, the upper side is wider and the lower side is narrower as shown in FIG. 5, or the upper side is narrower and the lower side is wide as shown in FIG. Or become.
[0003]
The operation of the fluid bearing configured as described above will be described below. When a motor (not shown) is energized, the shaft 1 or the sleeve 2 and the thrust plate 3 start rotating. The lubricant 4 generates pressure by the pumping action of the pressure generating grooves 2A, 2B, 3A, and rotates without contact.
[0004]
[Patent Document 1]
JP-A-3-163212
[Problems to be solved by the invention]
However, in recent years, fluid bearings are required to have higher precision than before.However, if the bearing gap between the shaft and the sleeve designed to be uniform is actually manufactured, the hollow portion of the sleeve is inclined, The bearing gap is not uniform, and the adverse effects have become significant. That is, as shown in FIG. 5, when the upper side of the sleeve hollow portion is wider and the lower side is narrower, the upper bearing gap of the radial bearing is wider and the lower bearing gap is narrower, and the lower bearing length of the lower bearing is smaller than that of the upper bearing. Since it is longer than the bearing length, the lubricant stagnates in the uneven part and it is difficult for it to flow to the thrust bearing side, the floating amount of the thrust bearing becomes smaller than the design value, and the adverse effect that thrust in the thrust direction appears, conversely, As shown in FIG. 6, when the upper side of the sleeve hollow portion is narrow and the lower side is wide, the upper bearing gap is narrow and the lower bearing gap is wide, and the upper bearing length of the upper bearing is longer than the lower bearing length. Therefore, the pumping action of the lubricant from the upper bearing becomes excessive, the floating amount of the thrust bearing becomes larger than a design value, and an adverse effect of causing the floating of the thrust bearing excessively appears.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the upper side of the hollow portion of the sleeve is designed wider and the lower side is narrowed, and then the upper side of the bearing gap of the radial bearing is widened and the lower side is narrowed. The length should be longer on the upper side and shorter on the lower side. Or, by design, the upper side of the sleeve hollow is narrower and the lower side is wider, then the upper side of the bearing gap is wider and the lower side is narrower, so that both the upper and lower bearings have a shorter bearing length so that the upper side is shorter and the lower side is longer. I do. In any case, the floating amount of the thrust bearing can be made appropriate, so that the thrust bearing is prevented from being displaced and the thrust bearing is prevented from floating excessively.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 4 show an embodiment of the present invention.
[0008]
(Embodiment 1)
FIG. 1 is a sectional view of the hydrodynamic bearing device according to the first embodiment. In FIG. 1, reference numeral 11 denotes a shaft, which is rotatably fitted together with a sleeve 12. A thrust plate 13 is in contact with an end face 11 </ b> A of the shaft 11 and is fixed to an end face of the sleeve 12. A pressure generating groove 13A is provided in the thrust plate 13, and a lubricant 14 is injected into the thrust plate 13 to constitute a thrust bearing. Pressure generating grooves 12A and 12B are provided on the inner periphery of the sleeve 12 or the outer periphery of the shaft 11, and a lubricant 14 is injected to constitute a radial bearing. Two radial bearings are provided. The sleeve 12 is designed to be wide on the upper side and narrow on the lower side. At this time, the bearing gap between the shaft 11 and the sleeve 12 is wide on the upper side and narrow on the lower side.
[0009]
The operation of the fluid bearing configured as described above will be described below. When a motor (not shown) is energized, the shaft 11 or the sleeve 12 and the thrust plate 13 start rotating. The lubricant 14 generates pressure by the pumping action of the pressure generating grooves 12A, 12B, 13A, and rotates without contact.
[0010]
Here, the unequal bearing lengths of the upper bearing 15 above the radial bearing and the lower bearing 16 below the radial bearing are set such that the upper length is longer than the lower length. Since the lower bearing length of the lower bearing 16 is short, the lubricant 14 flows into the thrust bearing without stagnation, thereby preventing the friction in the thrust direction. In the shape of the sleeve 12, overfloating of the thrust bearing does not originally occur.
[0011]
(Embodiment 2)
FIG. 2 is a sectional view of the hydrodynamic bearing device according to the second aspect. In FIG. 2, reference numeral 11 denotes a shaft, which is rotatably fitted together with the sleeve 12. A thrust plate 13 is in contact with an end face 11 </ b> A of the shaft 11 and is fixed to an end face of the sleeve 12. A pressure generating groove 13A is provided in the thrust plate 13, and a lubricant 14 is injected into the thrust plate 13 to constitute a thrust bearing. Pressure generating grooves 12A and 12B are provided on the inner periphery of the sleeve 12 or the outer periphery of the shaft 11, and a lubricant 14 is injected to constitute a radial bearing. Two radial bearings are provided. The sleeve 12 is made narrower on the upper side and wider on the lower side. At this time, the bearing gap between the shaft 11 and the sleeve 12 is narrow on the upper side and wide on the lower side.
[0012]
The operation of the fluid bearing configured as described above will be described below. When a motor (not shown) is energized, the shaft 11 or the sleeve 12 and the thrust plate 13 start rotating. The lubricant 14 generates pressure by the pumping action of the pressure generating grooves 12A, 12B, 13A, and rotates without contact.
[0013]
Here, the unequal bearing lengths of the upper bearing 15 on the upper side of the radial bearing and the lower bearing 16 on the lower side are set such that the length of the upper side is shorter than the length of the lower side. Since the lower bearing length of the upper bearing 15 is long, the lubricant 14 does not easily reach the lower bearing 16, so that the excess lubricant 14 does not easily turn around the thrust bearing, and the thrust bearing is prevented from floating excessively. it can. In addition, in the shape of the sleeve 12, the shear in the thrust direction does not originally occur.
[0014]
(Embodiment 3)
FIG. 3 is a sectional view of the hydrodynamic bearing device according to the third aspect. In FIG. 3, reference numeral 11 denotes a shaft, which is rotatably fitted together with the sleeve 12. A thrust plate 13 is in contact with an end face 11 </ b> A of the shaft 11 and is fixed to an end face of the sleeve 12. A pressure generating groove 13A is provided in the thrust plate 13, and a lubricant 14 is injected into the thrust plate 13 to constitute a thrust bearing. Pressure generating grooves 12A and 12B are provided on the inner periphery of the sleeve 12 or the outer periphery of the shaft 11, and a lubricant 14 is injected to constitute a radial bearing. Two radial bearings are provided. The sleeve 12 is narrower on the upper side of the upper bearing 15 above the radial bearing and wider on the lower side, and wider on the lower bearing 16 below the radial bearing and narrower on the lower side. At this time, the bearing gap between the shaft 11 and the sleeve 12 is narrower on the upper side in the upper bearing 15 and wider on the lower side, and is wider on the upper side in the lower bearing 16 and narrower on the lower side.
[0015]
The operation of the fluid bearing configured as described above will be described below. When a motor (not shown) is energized, the shaft 11 or the sleeve 12 and the thrust plate 13 start rotating. The lubricant 14 generates pressure by the pumping action of the pressure generating grooves 12A, 12B, 13A, and rotates without contact.
[0016]
Here, the unequal bearing length of the upper bearing 15 shortens the upper length and lengthens the lower length, and the unequal bearing length of the lower bearing 16 increases the upper length and lowers the lower length. Keep the length of Since the lower bearing length of the upper bearing 15 is long, the lubricant 14 does not easily reach the lower bearing 16, so that the excess lubricant 14 does not easily turn around the thrust bearing, and the thrust bearing is prevented from floating excessively. it can. Since the lower bearing length of the lower bearing 16 is short, the lubricant 14 flows into the thrust bearing without stagnation, thereby preventing the friction in the thrust direction.
[0017]
(Embodiment 4)
FIG. 4 is a sectional view of the hydrodynamic bearing device according to the fourth aspect. In FIG. 3, reference numeral 11 denotes a shaft, which is rotatably fitted together with the sleeve 12. A thrust plate 13 is in contact with an end face 11 </ b> A of the shaft 11 and is fixed to an end face of the sleeve 12. A pressure generating groove 13A is provided in the thrust plate 13, and a lubricant 14 is injected into the thrust plate 13 to constitute a thrust bearing. Pressure generating grooves 12A and 12B are provided on the inner periphery of the sleeve 12 or the outer periphery of the shaft 11, and a lubricant 14 is injected to constitute a radial bearing. Two radial bearings are provided. In addition, the sleeve 12 is designed to be wide above the upper bearing 15 above the radial bearing and narrow at the lower side, and narrow above the lower bearing 16 below the radial bearing and wide at the lower side. At this time, the bearing gap between the shaft 11 and the sleeve 12 is wide on the upper bearing 15 and narrow on the lower side, and on the lower bearing 16 is narrower on the upper side and wider on the lower side.
[0018]
The operation of the fluid bearing configured as described above will be described below. When a motor (not shown) is energized, the shaft 11 or the sleeve 12 and the thrust plate 13 start rotating. The lubricant 14 generates pressure by the pumping action of the pressure generating grooves 12A, 12B, 13A, and rotates without contact.
[0019]
Here, the unequal bearing length of the upper bearing 15 increases the upper length and shortens the lower length, and the unequal bearing length of the lower bearing 16 shortens the upper length and reduces the lower length. Make the length longer. Due to the shapes of the shaft 11 and the sleeve 12, it is possible to prevent the overfloating of the thrust bearing and to prevent the thrust in the thrust direction at the same time.
[0020]
【The invention's effect】
As is clear from the above, according to the inclination of the hollow part of the sleeve, the bearing length in a wide place is made longer and the bearing length in a narrow place is made shorter, so that thrust in the thrust direction and over-floating of the thrust bearing can be simultaneously achieved. To prevent.
[Brief description of the drawings]
1 is a sectional view showing a first embodiment of the present invention; FIG. 2 is a sectional view showing a second embodiment of the present invention; FIG. 3 is a sectional view showing a third embodiment of the present invention; FIG. 5 is a cross-sectional view showing a conventional hydrodynamic bearing device. FIG. 6 is a cross-sectional view showing a conventional hydrodynamic bearing device.
DESCRIPTION OF SYMBOLS 1 Shaft 1A End face 2 of shaft 1 Sleeve 2A Pressure generating groove 2B on inner circumference of sleeve 2 or outer circumference of shaft 1 Pressure generating groove 3 on inner circumference of sleeve 2 or outer circumference of shaft 1 Thrust plate 3A Pressure generating groove on thrust plate 3 Reference Signs List 4 Lubricant 5 Upper bearing of radial bearing 6 Lower bearing 11 of radial bearing 11 Shaft 11A End face 12 of shaft 11 Sleeve 12A Pressure generation groove 12B in inner circumference of sleeve 12 or outer circumference of shaft 11 Inner circumference of sleeve 12 or outer circumference of shaft 11 Pressure generating groove 13 in thrust plate 13A Pressure generating groove 14 in thrust plate 13 Lubricant 15 Upper bearing of radial bearing 16 Lower bearing of radial bearing

Claims (4)

A shaft and a sleeve rotatably fitted to the shaft are provided. A pressure generating groove is provided on one of an outer periphery of the shaft and an inner periphery of the sleeve, and a seal is provided between the pressure generating grooves. A radial bearing provided with a fluid that is a liquid or a gas at a place where it is provided, a thrust plate is provided on the end face of the shaft, and another pressure generating groove is provided on the thrust plate, and between the pressure generating groove In a fluid bearing configured with a fluid that is a liquid or a gas in a sealed place, the hollow portion of the sleeve is broadly narrowed on the upper side and lower on the lower side, and the bearing length of the radial bearing is on the upper side. A hydrodynamic bearing device characterized by being long and short on the lower side. A shaft and a sleeve rotatably fitted to the shaft are provided. A pressure generating groove is provided on one of an outer periphery of the shaft and an inner periphery of the sleeve, and a seal is provided between the pressure generating grooves. A radial bearing provided with a fluid that is a liquid or a gas at a place where it is provided, a thrust plate is provided on the end face of the shaft, and another pressure generating groove is provided on the thrust plate, and between the pressure generating groove In a fluid bearing configured with a fluid that is a liquid or a gas in a place sealed in a fluid bearing, the hollow portion of the sleeve is narrowed on the upper side and widened on the lower side, and the bearing length of the radial bearing is on the upper side. A hydrodynamic bearing device characterized by being short and long on the lower side. A shaft and a sleeve rotatably fitted to the shaft are provided. A pressure generating groove is provided on one of an outer periphery of the shaft and an inner periphery of the sleeve, and a seal is provided between the pressure generating grooves. A radial bearing provided with a fluid that is a liquid or a gas at a place where it is provided, a thrust plate is provided on the end face of the shaft, and another pressure generating groove is provided on the thrust plate, and between the pressure generating groove In a fluid bearing configured with a fluid that is a liquid or a gas in a sealed place, the hollow portion of the sleeve is narrower on the upper side in the upper bearing of the radial bearing, wider on the lower side, and in the lower bearing on the upper side. A hydrodynamic bearing device characterized in that the bearing length of the radial bearing is widened narrowly on the lower side, and the bearing length of the radial bearing is shorter on the upper side and longer on the lower side, and the lower bearing is longer on the upper side and shorter on the lower side. A shaft and a sleeve rotatably fitted to the shaft are provided. A pressure generating groove is provided on one of an outer periphery of the shaft and an inner periphery of the sleeve, and a seal is provided between the pressure generating grooves. A radial bearing provided with a fluid that is a liquid or a gas at a place where it is provided, a thrust plate is provided on the end face of the shaft, and another pressure generating groove is provided on the thrust plate, and between the pressure generating groove In a fluid bearing configured with a fluid that is a liquid or a gas in a sealed place, the hollow portion of the sleeve is narrower on the upper side in the upper bearing of the radial bearing, narrower on the lower side, and on the upper side in the lower bearing. Hydrodynamic bearing device characterized in that the radial bearing is narrower and wider on the lower side, and the bearing length of the radial bearing is longer on the upper side and shorter on the lower side, and shorter on the upper side and shorter on the lower side in the lower bearing.

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