JP2004100870A - Self-aligning type fluid dynamic-pressure bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-aligning type fluid dynamic-pressure bearing capable of easily securing high straightness, and achieving a long service life. <P>SOLUTION: This self-aligning type fluid dynamic-pressure bearing 1 to be used as connected to an external shaft is provided with a bearing main body 4 having a shaft hole 9 to rotatably contain a shaft 7, an oil groove 11 in a circumferential surface of the shaft hole, and a spherical surface 5 at least partly, and a support body 6 having an inner wall 6a to form a space for containing the bearing main body to support the bearing main body in such a way that an axial line of the shaft hole freely oscillates in accordance with motion of the shaft while the inner wall is in contact with the spherical surface. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a self-aligning fluid dynamic pressure bearing, and more particularly, to a self-aligning fluid dynamic pressure bearing having a dynamic pressure groove and capable of self-alignment.
[0002]
[Prior art]
In a conventional fluid dynamic bearing, as shown in FIG. 5, dynamic pressure grooves 102 are generally formed at two locations on a peripheral surface of a shaft hole of a sleeve 101 at predetermined intervals. This bearing is often used for a flat type spindle motor, and a motor shaft 104 is rotatably supported in a shaft hole of the sleeve 101, and a rotor connected to the motor shaft 104 is uniaxially supported.
[0003]
As a long and thin type motor bearing, one having a pair of bearings 112 and 113 on both sides of a rotor 110 as shown in FIG. 6 is known. As the bearings 112 and 113, ball bearings are widely used.
[0004]
[Patent Document 1]
JP 10-131953 A
[Problems to be solved by the invention]
When trying to use a fluid dynamic pressure bearing as a bearing for a long and thin type motor, there are the following problems.
[0006]
It is not easy to obtain the straightness of the bearings mounted at two places, and especially in the case of a fluid dynamic pressure bearing, the clearance between the shaft and the dynamic pressure groove is as small as several μm. It is difficult to get high straightness across.
[0007]
Further, since the fluid dynamic pressure bearing is open on both sides, the supplied oil disappears quickly, and when the oil is depleted, it becomes inoperable, so that there is a problem that the life of the fluid dynamic pressure bearing is short.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a self-aligning type fluid dynamic pressure bearing which solves the above-mentioned problems of the related art, can easily secure high straightness, and has a long life.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a self-aligning type fluid dynamic pressure bearing of the present invention is a self-aligning type dynamic pressure bearing which is used by being connected to an external shaft. Is formed, an oil groove is formed on a peripheral surface of the shaft hole, and the bearing body has a spherical surface in at least a part thereof; and an inner wall that forms a space for accommodating the bearing body. And a support for supporting the bearing body such that the axis of the shaft hole can swing freely in accordance with the movement of the shaft while contacting the shaft.
[0010]
Further, the oil groove is arranged on both sides with respect to a center portion of the shaft hole.
[0011]
Further, the oil groove is arranged in a band shape one by one on both sides with respect to a center portion of the shaft hole.
[0012]
Further, an oil storage portion for storing oil so that oil can be supplied to the oil groove is provided on an outer wall surface of the bearing body.
[0013]
Further, the oil storage portion has a plurality of storage grooves for storing oil formed at intervals on an outer wall surface of the bearing body.
[0014]
Further, the oil storage section has at least one communication hole formed in the bearing main body, which communicates the storage groove with the oil groove.
[0015]
In addition, a frame for accommodating the support is provided, and at least one oil injection hole for supplying oil to the oil storage portion is formed in the frame.
[0016]
Further, the oil injection hole is closed by a closing member after supplying the oil to the oil reservoir.
[0017]
In the above-described invention, the support supports the bearing main body while bringing its inner wall into contact with the spherical surface of the bearing main body, and supports the bearing main body such that the axis of the shaft hole can swing freely. When the axial direction is constrained due to connection with, for example, another self-aligning type bearing or the like, alignment of the bearing body can be automatically performed, and high straightness can be easily secured.
[0018]
Also, since the oil grooves are arranged on both sides with respect to the center of the shaft hole, the shaft can be prevented from being excessively inclined in the shaft hole, and the shaft contacts the end of the shaft hole to form the shaft hole. Wear can be prevented.
[0019]
In addition, since the oil reservoir is provided, oil shortage in the fluid dynamic bearing can be eliminated, and the life can be extended.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
The self-aligning type dynamic pressure bearing 1 is used by being connected to an external shaft such as a motor shaft. The bearing main body 4 has a spherical surface 5 at least in part, and a support 6 supporting the bearing main body 4. And Here, the external shaft is, for example, a self-aligning type dynamic pressure bearing according to the present invention, or another self-aligning type bearing of another bearing type, or a bearing having an appropriate play with respect to the shaft. And so on.
[0022]
A shaft hole 9 is formed in the center of the bearing main body 4 and penetrates both ends, and has a cylindrical hole for rotatably housing the shaft 7. A large number of V-shaped oil grooves 11 are formed in the cylindrical peripheral surface of the shaft hole 9. The oil grooves 11 are arranged in a band at small intervals in a direction orthogonal to the axis 10 of the shaft hole 9.
[0023]
As shown in FIG. 1, the belt-shaped oil grooves 11, 11 are arranged one by one at substantially symmetrical positions on opposite sides of the axial center of the shaft hole 9. The belt-shaped oil grooves 11, 11 are not arranged at the center of the shaft hole 9. As described above, since the oil grooves 11 arranged in a band shape are arranged one by one at substantially symmetric positions with respect to the center of the shaft hole 9, the shaft 7 sandwiches the center of the shaft hole 9. Since the dynamic pressure is received from the oil grooves 11 on both sides, the bearing body 4 can be prevented from being excessively inclined with respect to the shaft 7 connected to an external shaft or the like and having a predetermined direction. For example, when there is only one oil groove 11 arranged in a band shape at the center of the shaft hole 9, the bearing body 4 may be excessively inclined with respect to the shaft 7, and in this case, the shaft 7 There is a problem that the shaft hole 9 comes into contact with the end of the shaft hole 9 and the shaft hole 9 is worn. The phenomenon that the shaft 7 comes into contact with the end of the shaft hole 9 and wears the shaft hole 9 does not occur in a bearing that is not of the self-aligning type, and may occur particularly in the self-aligning type dynamic pressure bearing. In this regard, it is very effective to arrange the band-shaped oil grooves 11 on both sides with respect to the center of the shaft hole 9 as described above.
[0024]
The bearing body 4 is swingably supported by a support 6 on a spherical surface 5. The bearing body 4 has a portion other than the spherical surface 5 cut away from the spherical surface to form a cylindrical surface 5a.
[0025]
The support 6 has an inner wall 6 a that forms a space for accommodating the bearing body 4. The support body 6 supports the bearing body 4 while making the inner wall 6 a contact the spherical surface 5, and supports the bearing body 4 so that the axis 10 of the shaft hole 11 can swing freely following the swing of the shaft 7. I do.
[0026]
The support 6 includes a first housing 13 made of a metal plate and having a hemispherical concave portion 13b and a cylindrical portion 13c extending from the concave portion 13b. And a second housing 15 formed of a block-shaped resin material. The second housing 15 is housed inside the cylindrical portion 13c of the first housing 13. At the top of each of the first housing 13 and the second housing 15, holes 13a and 15a are formed for penetrating and attaching the shaft 7, and the holes 13a and 15a enable the shaft 7 to be aligned and the shaft 7 to be mounted. Has a diameter larger than the diameter of the shaft 7 so as to allow the swing of
[0027]
A frame 17 is provided outside the first housing 13 and the second housing 15. The frame 17 has a bottom 17a, a side 17b, and an end 17c, and is in contact with the second housing 15 at the bottom 17a. An adhesive 19 is inserted between the inside of the side portion 17b and the outside of the concave portion 13b of the first housing 13, and the frame 17 and the first housing 13 are fixed by the adhesive 19. The end portion 17c of the frame body 17 extends 90 degrees outward from the side portion 17b, and can be used as a mounting portion to an external member.
[0028]
As described above, the support body 6 supports the bearing body 4 while bringing the inner wall 6a into contact with the spherical surface 5 so that the axis 10 of the shaft hole 9 can swing freely in the direction in which the shaft 7 should face. 4, the shaft 7 has an external shaft (for example, a self-aligning dynamic pressure bearing according to the present invention, another self-aligning type bearing of another bearing type, or a bearing having an appropriate play with respect to the shaft 7). When the shaft 7 swings, for example, when the shaft 7 swings, the shaft 7 can be aligned and the bearing body 4 can be supported.
[0029]
An oil injection hole 21 is formed in the side portion 13b of the first housing 13, and an oil injection hole 22 is formed in the frame 17 at a position corresponding to the oil injection hole 21. Oil can be supplied to an oil supply groove 25 described later formed in the bearing body 4. After the oil is supplied, the oil injection hole 22 of the frame 17 is closed by the lid 23.
[0030]
Next, with reference to FIG. 2 and FIG. 3, an oil storage portion 24 for storing oil, which is formed by a plurality of oil supply grooves 25 formed in the bearing main body 4, will be described.
[0031]
In the example shown in FIG. 2, the oil supply groove 25 is formed linearly vertically on the cylindrical surface 5 a of the bearing main body 4, and at a central portion of the oil supply groove 25 at a position corresponding to the oil injection holes 21 and 22. A communication hole 27 is formed. A plurality of oil supply grooves 25 are formed at equal intervals, and a total of two communication holes 27 are formed at positions opposed by 180 degrees.
[0032]
When the lid 23 is removed and oil is supplied from the oil injection holes 21 and 22, the supplied oil enters the shaft hole 9 through the communication hole 27 and is supplied to the oil groove 11.
[0033]
In the example shown in FIG. 3, the oil groove 25 is formed linearly vertically on the cylindrical surface 5 a and the spherical surface 5 of the bearing main body 4, and communicates with the shaft hole 11 at the upper and lower ends of the spherical surface 5. I have. In the example shown in FIG. 3, the communication hole 27 in the case of FIG. 2 is not formed. When the lid 23 is removed and oil is supplied from the oil injection holes 21 and 22, the supplied oil enters the shaft hole 9 from the upper and lower ends of the spherical surface 5 and is supplied to the oil groove 11.
[0034]
FIG. 4 shows an example in which two self-aligning type fluid dynamic pressure bearings 1 and 2 are connected by a common shaft 7. The self-aligning type fluid dynamic pressure bearing 1 and the self-aligning type fluid dynamic pressure bearing 2 are arranged at positions where the bottom portions 17a of the frame 17 are opposed to each other. The self-aligning fluid dynamic pressure bearing 1 is the same as that shown in FIG. 1, and the self-aligning fluid dynamic pressure bearing 2 has substantially the same structure as the self-aligning fluid dynamic pressure bearing 1. In the self-centering type fluid dynamic pressure bearing 2, unlike the case of the self-centering type fluid dynamic pressure bearing 1, a protrusion for accommodating the end of the shaft 7 is provided at the top of the semi-spherical recess 13 b of the first housing 13. A body 13c is formed.
[0035]
In FIG. 4, the frames 17 of the self-aligning type fluid dynamic pressure bearings 1 and 2 are arranged and aligned, and the common shaft 7 is passed through the shaft holes 9 and 9 of the self-aligning type fluid dynamic pressure bearings 1 and 2. In this case, even when the respective axes 10 and 10 of the shaft holes 9 and 9 are displaced from each other, the support 6 supports the bearing body 4 while keeping the inner wall 6 a in contact with the spherical surface 5 and swings the shaft 7. Since the bearing main body 4 is supported so that the axis 10 of the shaft hole 11 can swing freely following the movement, the shaft 7 swings when the shaft 7 swings when the shaft 7 is connected to an external shaft. And the bearing body 4 can be supported.
[0036]
Since the support 6 supports the bearing body 4 so that the axis 10 of the shaft hole 11 can swing freely, the centering of the bearing body 4 is performed over the two self-aligning type fluid dynamic pressure bearings 1 and 2. It can be performed.
[0037]
It should be noted that a normal bearing that rotatably supports the shaft 7 is used instead of the self-aligning type fluid dynamic pressure bearing 2 in FIG. The centering type fluid dynamic pressure bearing 1 can exhibit the function of self-centering.
[0038]
As described above, according to the embodiment of the present invention, the support 6 supports the bearing main body 4 while making the inner wall 6 a contact the spherical surface 5, and follows the shaft 7 so that the axis 10 of the shaft hole 11 can swing freely. Therefore, when the shaft 7 is connected to an external shaft or the like, the bearing main body 4 can be aligned and the bearing main body 4 can be supported.
[0039]
2 and 3, the oil supply groove 25 constituting the oil storage portion 24 has a certain groove volume, so that the oil required for the oil groove 11 can be supplied as needed over a long period of time. . As a result, oil shortage in the fluid dynamic bearing can be eliminated, and the life can be extended.
[0040]
【The invention's effect】
As described above, according to the configuration of the present invention, since the support supports the bearing main body such that the axis of the shaft hole can swing freely in the direction in which the shaft should face, the shaft is connected to the external shaft. In such cases, the alignment of the bearing body can be automatically performed, and high straightness can be easily secured.
[0041]
Also, since the oil grooves are arranged on both sides with respect to the center of the shaft hole, it is possible to prevent the bearing main body from being excessively inclined with respect to the shaft whose axial direction is determined by connection with an external shaft, etc. Does not contact the end of the shaft hole and wear the shaft hole.
[0042]
In addition, since the oil reservoir is provided, oil shortage in the fluid dynamic bearing can be eliminated, and the life can be extended.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a self-aligning type fluid dynamic bearing according to the present invention.
FIG. 2 is a perspective view showing one embodiment of a bearing body.
FIG. 3 is a perspective view showing another embodiment of the bearing body.
FIG. 4 is a cross-sectional view showing an example in which two self-aligning type fluid dynamic bearings are connected.
FIG. 5 is a sectional view showing an example of a conventional fluid dynamic pressure bearing.
FIG. 6 is a sectional view showing another example of the conventional fluid dynamic bearing.
[Explanation of symbols]
1, 2 Self-aligning type fluid dynamic pressure bearing 4 Bearing body 5 Spherical surface 5a Cylindrical surface 6 Support member 7 Shaft 9 Shaft hole 10 Axis line 11 Oil groove 13 First housing 15 Second housing 17 Frame 21, 22 Oil injection hole 24 oil reservoir 25 oil supply groove

Claims (8)

A self-aligning dynamic pressure bearing used by being connected to an external shaft,
A shaft body for rotatably housing a shaft is formed, an oil groove is formed on a peripheral surface of the shaft hole, and a bearing body having a spherical surface at least in part;
An inner wall forming a space for accommodating the bearing main body, and supporting the bearing main body such that an axis of the shaft hole can swing freely according to the movement of the shaft while the inner wall is in contact with the spherical surface. Support,
A self-aligning fluid dynamic pressure bearing comprising: The self-aligning fluid dynamic pressure bearing according to claim 1, wherein the oil grooves are arranged on both sides with respect to a center portion of the shaft hole. 3. The self-aligning type fluid dynamic bearing according to claim 2, wherein the oil grooves are arranged in a band shape one at each side with respect to a center portion of the shaft hole. The self-aligning type fluid dynamic pressure bearing according to claim 1, wherein an oil storage portion that stores oil so that oil can be supplied to the oil groove is provided on an outer wall surface of the bearing body. The self-aligning type fluid dynamic pressure according to claim 4, wherein the oil storage portion has a plurality of storage grooves for storing oil formed at intervals on an outer wall surface of the bearing body. bearing. The self-aligning type fluid dynamic bearing according to claim 5, wherein the oil storage portion has at least one communication hole formed in the bearing body that communicates the storage groove and the oil groove. . A frame for accommodating the support,
The self-aligning type fluid dynamic pressure bearing according to claim 4, wherein at least one oil injection hole for supplying oil to the oil storage portion is formed in the frame body. The self-aligning type fluid dynamic bearing according to claim 7, wherein the oil injection hole is closed by a closing member after supplying the oil to the oil storage portion.

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