JP2005106095A - Bearing device for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor using a sintered oil-retaining bearing, which improves rotation accuracy without using special machining accuracy or a structure with high precision, and has good durability. <P>SOLUTION: The bearing device for the motor is structured by superimposing a plurality of the sintered oil-retaining bearings having shaft insertion holes in an axial direction. One or more identification marks are provided on the bearing, and each bearing is disposed at a position that is rotated about the identification mark by a predetermined angle when superimposed. Therefore, the bearings having the same shapes are rotated, thereby decreasing a substantial difference between a diameter of the shaft insertion hole and a rotation shaft. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor bearing device, and more particularly to a bearing device that is used in a state where a plurality of sintered oil-impregnated bearings are stacked.

Various motors are used in audio equipment such as CD players, VTRs, and video disc players.
The motor shown in FIG. 6 is an example of a brushless motor used for a spindle motor or the like of a disk device. In FIG. 6, the cross section of the main part is shown by hatching on the right side of the center line.
Reference numeral 1 denotes a driving rotary shaft, and 2 denotes a rotor that rotates together with the rotary shaft 1. The rotor 2 includes a rotor case 3 to which the rotating shaft 1 is fixed, and a magnet 4 attached over the entire circumference of the circumferential portion of the rotor case 3.
The stator base 6 is formed of a thin plate, and a cylindrical bearing holder 7 is fixed by caulking. A bearing 8 is fitted in the bearing holder 7 and supports the rotary shaft 1 to be rotatable. The bearing holder 7 has a shape sealed on the lower side of the drawing, and supports the lower end of the rotary shaft 1 via a thrust receiving sheet 13.
In addition, a washer 11 is used to prevent the rotor from coming off.
A plate 20 is attached to the upper end of the bearing holder 7 in the drawing. The plate 20 is attached to prevent the lubricating oil impregnated in the bearing 8 from scattering.

A stator core 9 around which a coil 10 is wound is fixed on the outer peripheral side of the bearing holder 7, and the terminal of the coil 10 is soldered to a connection pattern (not shown) of a flexible substrate 12 provided on the upper surface of the stator base 6. Connected with.
The lower side of the bearing 8 (stator base side) is provided with a concave portion 19 at the inner central portion of the bearing 8, so that the outer diameter is narrowed smaller than the other portions, and a small diameter portion 18 is formed. The rotating shaft 1 is rotatably supported in the vicinity of both ends of the bearing 8 by the recess 19.

A plurality of grooves 17 are formed on the outer peripheral surface of the bearing 8 in the axial direction. This groove has a function of venting air when the rotary shaft 1 is inserted into the bearing 8 mounted on the bearing holder 7.
An example of such a configuration is, for example, Japanese Patent Application Laid-Open No. 2003-79095 previously filed by the present applicant.
Japanese Patent Laid-Open No. 2002-195259 also shows a similar configuration.

JP 2003-79095 A JP 2002-195259 A

In recent years, as the recording density of disks has increased and the rotation speed has increased, rotation accuracy such as the perpendicularity of the rotation axis and high durability of rotation have been required.
Regarding the rotational accuracy, the clearance between the shaft and the bearing is greatly affected, and a smaller clearance is required. In order to further reduce the clearance between the shaft and the bearing, advanced technology is required for processing for manufacturing the shaft and the bearing.
In addition, regarding the durability, it is necessary to retain the oil impregnated in the bearing, and it is necessary to retain the oil in the bearing without scattering the oil due to the rotation of the shaft. For that purpose, a structure for holding a scattering prevention mechanism and oil is required.
An object of the present invention is to provide a motor bearing device having high rotational accuracy and high durability at the same time without using a particularly advanced processing technique.

In order to solve the above-described problem, a motor bearing device according to claim 1 of the present application is a motor bearing device in which a plurality of sintered oil-impregnated bearings having shaft insertion holes are stacked in the axial direction, and the bearing One or more identification marks are provided on the bearings, and when a plurality of the bearings are stacked, each bearing is arranged at a position rotated by a predetermined angle with reference to the identification marks.
With this configuration, by using a combination of a plurality of bearings that are offset by a certain angle, a substantial shaft hole diameter is set on the shaft by utilizing a slight center misalignment between the shaft insertion hole and the outer periphery that are generated when the bearing is manufactured. It becomes possible to match.
At the same time, the shape necessary for manufacturing the cylindrical bearing enables oil to be held without requiring a separate configuration.
Further, when the identification mark according to claim 2 has a configuration in which three or more of the identification marks are formed with different arrangement angles, a special device for shifting the bearing by a certain angle is not necessary, and a plurality of bearings can be easily rotated in the rotation direction. Can be assembled by shifting
Furthermore, if the said identification mark of Claim 3 is a groove | channel formed in the said annular outer peripheral surface in the axial direction, the groove | channel which is an identification mark can be utilized as a groove | channel of an air release, and a shaft is a bearing apparatus. It becomes easy to attach to.

The bearing device of the motor of the present invention can be configured to easily configure the bearing with high accuracy and to have high durability by taking advantage of the characteristic of dimensional variation generated in the manufacture of the bearing.
In other words, it does not require special high-precision bearings or high-precision machined shafts, and as a whole, the rotational accuracy is increased, and a special oil holding mechanism is not required. realizable.

A motor M is shown in FIG. 1 as an example using the bearing device of the present application. The same components as those in the conventional example of FIG.
The bearing holder 70 of the motor M is formed in a cylindrical shape, and is press-fitted in such a manner that a plurality of (in this case, two) annular bearings 30 are overlapped from the openings at both ends so as to project the shaft center. In this case, two sets of bearings 30 are provided on the lower end side of the rotating shaft 1 and the upper end side of the bearing holder 70. The lower end side of the bearing holder 70 is closed with a cap 71.
The overlapped bearings 30 are shifted in the rotational direction by a predetermined angle with reference to the identification marks provided on the bearings, and are attached to the bearing holder 70 by press fitting.

FIG. 2 shows a configuration of a bearing 30 that is a sintered oil-impregnated bearing according to an embodiment of the present invention. FIG. 2A is a plan view, and FIG. 2B shows a cross-sectional view of the main part of the side view.
The bearing 30 is a sintered oil-impregnated bearing formed so that the outer peripheral portion 31 and the shaft insertion hole 32 are concentric. The bearing 30 has a predetermined thickness, and the cylindrical upper surface 35 and the shaft insertion hole of the upper and lower surfaces 33 and 34 and the outer peripheral portion 31. An outer peripheral chamfer 37 and an inner peripheral chamfer 38 are formed at a portion where 32 cylindrical inner surfaces 36 intersect.
Although the cylindrical outer surface 35 and the cylindrical inner surface 36 are required to be completely concentric, in order to be completely concentric, a highly accurate manufacturing mold is required, and in order to manufacture such a mold. Advanced processing technology and accuracy control are required.

Therefore, the bearing is actually formed in an eccentric state in the range of several microns.
The diameter of the cylindrical inner surface 36 forming the shaft insertion hole 32 is set with only a plus tolerance with respect to the nominal dimension, and is set within a range of several microns (for example, +0.005 to 0.015 millimeter).
It is known that the eccentric amount and the diameter are substantially constant when, for example, the same lot is produced from one mold. If the molds to be manufactured are different, there are many cases where the same nominal size is different within the tolerance range.

The accuracy of the drive shaft 1 is determined by the straightness of the shaft, the variation in diameter, and the like, but here, the variation in diameter is mainly handled.
The nominal size of the diameter of the drive shaft 1 is the same as the nominal size of the bearing, but the tolerance is set only with a minus tolerance, contrary to the case of the bearing, and also has a width of several microns (for example, −0.005 to −0. 015 millimeters).
Also in the case of the shaft, it is known that the variation in dimensions within the same lot to be processed is much smaller than when the lot is changed.

One concave identification mark 39 is provided on the upper surface 33 of the bearing 30. The identification mark 39 is provided on the upper surface 33 so as to cover the outer peripheral chamfer 37, but only the upper surface 33 or only the outer peripheral chamfer 37 may be formed as a recess. Further, the concave shape is not limited to a circular shape, and may be any shape that can identify the position in the circumferential direction.
Now, an ideal shaft insertion hole 32A completely concentric with the cylindrical outer surface 35 of the bearing 30 is indicated by a one-dot chain line. It is assumed that the actual shaft insertion hole 32 is decentered by a distance of a micrometer from the identification mark 39 in the angle direction of α ° and is formed with a diameter d.

Next, a usage pattern in which the bearing 30 is used in an overlapping manner will be described with reference to FIG. FIG. 3A is a plan view showing a state in which the identification mark is attached to the bearing holder 70 while being shifted by 90 degrees. FIG. 3B is a cross-sectional view of the main part viewed from the side. The identification marks are stacked so as to face in the same direction (upward direction in FIG. 3B), and are shifted in the rotation direction.
Here, it is assumed that the nominal size of the bearing is 2 mm, the actual diameter d is 2.015 mm, and the deviation amount a is 4 micrometers.
In this case, the diameter of the substantial shaft insertion hole is a dimension obtained by subtracting 1.4 times the diameter a from the diameter d, that is, 2.00094 micrometers obtained by subtracting 0.0056 from 2.015, and one bearing was used. The clearance to the shaft can be made smaller than in the case.
Further, when the bearing 30 is mounted 180 degrees shifted, the substantial diameter of the shaft insertion hole is 2.007 micrometers.
In this way, even when the diameter of the shaft insertion hole of the bearing actually completed is large, if there is little variation like the same lot with the same mold, the clearance between the shaft and the bearing can be changed by using multiple layers and shifting by a predetermined angle. Can be reduced, the rotational accuracy of the shaft can be increased, and the occurrence of abnormal noise can be prevented.

Further, by overlapping the bearings 30, the overlapping portions of the peripheral chamfer 37 become voids, which serve as oil reservoirs. In addition, the upper bearing serves to prevent oil scattering.
With such a configuration, the bearing itself constitutes an oil reservoir and a configuration for preventing scattering, so that each action can be obtained without providing a separate member.

FIG. 4 shows another embodiment according to the present invention, and shows an example in which a plurality of identification marks different in shape from the bearing 30 are provided. FIG. 4A is a plan view thereof, and FIG. 4B is a cross-sectional view of the main part of the side view thereof.
FIG. 4A is a plan view showing a state in which the identification mark is attached to the bearing holder 70 while being shifted by 90 degrees. FIG. 4B is a cross-sectional view of the main part viewed from the side. The same components as those of the bearing 30 are denoted by the same reference numerals and description thereof is omitted.
Identification marks 49a, 49b, and 49c are arranged on the outer peripheral portion 31 of the bearing 40 at intervals of a predetermined angle. It is assumed that the identification mark 49a is formed at a position α from the direction of displacement of the shaft insertion hole 32 as in FIG.
The identification mark 49b is formed at a position 90 degrees away from the identification mark 49a, and the identification mark 49c is formed at a position 30 degrees away from the identification mark 49b.
Further, the special mark 49a, 49b, 49c is formed in a groove shape that is inserted from the upper surface 33 side to the lower surface 34 side when mounted on the bearing holder 70.
The intervals at which the identification marks 49a, 49b, 49c are formed can be determined as appropriate if they do not have the same angle.

FIG. 5 shows a configuration when the bearing 40 is mounted on the bearing holder 70 while being shifted in the rotational direction. This is a structure in which the lower bearing 40 is overlapped while being shifted by 90 degrees relative to the upper bearing 40.
FIG. 5A is a plan view showing a state in which it is attached to the bearing holder 70 while being shifted by 90 degrees using the identification mark, and FIG. 5B is a cross-sectional view of the main part as viewed from the side. In the configuration of FIG. 3, some measuring instrument is required to shift the bearing 30 in the rotation direction. However, in the bearing 40, if the groove-shaped identification marks 49 a and 49 b are overlapped, the bearing 30 is shifted by 90 degrees in the rotation direction. It becomes a state.
Here, when the identification marks 49a and 49c are overlapped, the configuration is shifted by 30 degrees. The shift amount and the mark position can be determined as appropriate.

The identification marks 49a, 49b, 49c are formed in a groove shape as described above. If the identification mark is attached in a superimposed manner when it is attached to the bearing holder 7 while being shifted in the rotational direction, a hole through which air or oil passes is formed on the upper and lower sides of the overlapped bearing 40.
In the case where the bottom is sealed as in the case of the bearing holder 7, when the shaft 1 is attached to the bearing, it is necessary to provide an air vent groove on the bearing or the bearing holder. However, the identification mark is provided as in the second embodiment. When formed in a groove shape, it is possible to use both the identification mark and the groove.

  A motor using a sintered oil-impregnated bearing can provide a highly accurate motor such as a spindle motor used for disk drive.

It is the side view which showed the structure of the motor by embodiment of this invention. It is a figure which shows the detail of the bearing of this invention (Example 1). (Example 1) which shows the structure of the use condition of the bearing shown in FIG. It is a figure which shows the other Example details of the bearing of this invention (Example 2). (Example 2) which is a figure which shows the structure of the use condition of the bearing shown in FIG. It is a side view which shows the structure of the conventional motor.

Explanation of symbols

1 Rotating shaft 2 Rotor 6 Stator base 7 Bearing holder 30, 40 Bearing 39, 49 Identification mark

Claims (3)

  A bearing device of a motor configured by stacking a plurality of annular sintered oil-impregnated bearings having a shaft insertion hole in the axial direction, each of which is provided with one or more identification marks, and when the plurality of bearings are stacked, The motor bearing device is characterized in that the bearing is arranged at a position rotated by a predetermined angle with reference to the identification mark.   The bearing device according to claim 1, wherein three or more of the identification marks are formed at different arrangement angles.   3. The bearing device according to claim 1, wherein the identification mark is a groove formed in the annular outer peripheral surface in the axial direction.

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