JPH11155254A - Dynamic-pressure bearing motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic-pressure bearing motor, in which the circulating passage of a dynamic-pressure generating oil is composed of a simple structure and in which the dynamic-pressure generating oil does not leak to the outside. SOLUTION: Recessed parts are formed in either or both of the outer circumferential faces of sleeves 4, 12 and the inner circumferential face of a bearing housing 3. An axial-direction gap which is composed of the recessed parts by the insertion and bonding relationship between the sleeves 4, 12 and the bearing housing is used as the circulating passage of a dynamic-pressure generating oil, and a gap which is formed in such a way that a recessed part 13a connected to the outer circumference from the inner circumference of an end face part and a spacer to which a C-face is executed to an end face part on the outer circumference are arranged between the two sleeves 4, 12 which support and bear a shaft 1 is used as the circulating passage for the dynamic-pressure generating oil. Thereby, the dynamic-pressure generating oil can be circulated through a simple structure, and the lubricating property of the dynamic-pressure generating oil is maintained so as to restrain its deterioration. Thereby, the durability and the reliability of a dynamic-pressure bearing motor can be improved sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrodynamic bearing motor, and more particularly, to a method for circulating dynamic pressure generating oil in a hydrodynamic bearing, and preventing leakage of dynamic pressure generating oil. It is about.

[0002]

2. Description of the Related Art Conventionally, as a bearing structure of a spindle motor such as a CD-ROM or the like, there is a structure using a hydrodynamic bearing structure. For example, there is a structure described in JP-A-8-163821. .

In the above-described apparatus, a hole is formed on the upper end surface of the thrust plate to open toward the thrust cover, and a hole is formed in a portion of the shaft surface corresponding to the radial bearing portion where substantially maximum dynamic pressure is generated. A communication path was formed by these holes. Further, the fluid lubricant interposed in the thrust bearing portion is moved to the shaft side. As a result, the fluid lubricant flows from the radial bearing portion to the thrust bearing portion through the communication passage, and forms a circulation path that recirculates to the radial bearing portion.

[0004]

However, in the above configuration, since the annular passage must be provided in the same member in the thrust direction and the radial direction, the processing becomes very difficult, and the cost is increased. . Further, since the output end and the non-output end of the annular passage communicate with the inside of the motor or the outside of the motor, there is a possibility that the fluid lubricant may leak to portions other than the bearing portion, or at worst, to the outside.

Accordingly, the present invention solves the above-mentioned problems, prevents leakage of dynamic pressure generating oil in a dynamic pressure bearing with a simple structure, and enables the oil to be retained for a long period of time, thereby achieving a long service life. It is another object of the present invention to provide a hydrodynamic bearing motor with high reliability.

[0006]

According to the present invention, a concave portion is formed on one or both of an outer peripheral surface of a dynamic pressure generating sleeve and an inner peripheral surface of a bearing housing for holding the sleeve. An axial gap formed by an insertion relationship with a bearing housing, a concave portion provided on an end face of a spacer sandwiched between two sleeves supporting the rotating shaft and connected from an inner periphery to an outer periphery, By forming a circulation path for the dynamic pressure generating oil by communicating with the gap formed by the C surface formed on the outer peripheral end face of the spacer, it is possible to achieve good circulation of the dynamic pressure generating oil with a simple structure, Leakage of the generated oil is prevented, and the supply of the dynamic pressure generating oil is always stabilized, so that the durability and reliability thereof can be significantly improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydrodynamic bearing type motor according to the present invention is characterized in that an outer peripheral surface of a shaft or an inner peripheral surface of the sleeve rotatably supported via a sleeve disposed in a bearing housing. In a motor bearing structure in which a dynamic pressure generating groove is formed on one of the shafts and a dynamic pressure generating oil is interposed between the shaft and the sleeve, an outer peripheral surface of the sleeve or an inner peripheral surface of the bearing housing is formed. A concave portion is formed in one or both of the concave portions, and the concave portion is sandwiched between an axial gap formed by an insertion relationship between the sleeve and the bearing housing, and two sleeves supporting the rotary shaft. A spacer is provided on the surface in contact with the sleeve and communicates with a concave portion communicating from the inner periphery to the outer periphery to form a circulation passage for the dynamic pressure generating oil.

According to a second aspect of the present invention, two sleeves for supporting the rotating shaft and a metal spacer sandwiched between the two sleeves and having a C-plane formed on at least one of adjacent outer peripheral surfaces. And the C surface may be added as a circulation passage for the dynamic pressure generating oil.

The material of the spacer may be a sintered metal or a resin.

[0010]

FIG. 1 is a cross-sectional view of a spindle motor according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a main part showing a configuration of a circulation passage for dynamic pressure generating oil in FIG. FIG. 3 is a sectional view taken along the line AA of FIG. In FIG. 1, reference numeral 1 denotes a shaft on which a dynamic pressure generating groove 1a is formed. Sleeves 4 and 12 are fixed to the inner peripheral surface of a bearing housing 3 fixed to the stator base 2 by caulking or the like. .

A dynamic pressure generating oil is interposed between the sleeve 4, the spacer 13 and the shaft 1, and the shaft 1 is rotatably supported via the sleeve 4. The dynamic pressure generating groove 1 a may be formed on the inner peripheral surface of the sleeve 4 in addition to the outer peripheral surface of the shaft 1.
The stator core 5 is fixed to the outer peripheral surface of the bearing housing 3. The stator core 5 is provided with a plurality of coils 6.

On the other hand, a cup-shaped rotor yoke 7 is fixed to the shaft 1 by press-fitting or the like, and a ring-shaped magnet 8 is arranged on the inner peripheral surface of the rotor yoke 7 through a predetermined gap in the stator core 5. I have. When the shaft 1 is rotated by the magnetic action of the stator core 5 and the field magnet 8, the spindle motor having the above-described structure is moved between the shaft 1 and the sleeve 4 by the dynamic pressure generating groove 1 a and the dynamic pressure generating oil. Generates a dynamic pressure, whereby a high-precision motor with reduced shaft runout can be obtained.
Reference numeral 9 denotes a thrust receiver that holds the rotating shaft 1 in the thrust direction.

FIG. 3 is a sectional view taken along line AA of FIG. 2, and the inner circumferential surface of the bearing housing 3 has a keyway 3a in the axial direction.
Are formed. The shape of the key groove 3a is not limited to the illustrated one, but may be a triangle, an R shape, or the like. When the sleeve 4 is inserted into the inner peripheral surface of the bearing housing 3 configured as described above, the keyway 3a is directly formed as the gap 10 in the axial direction.

The spacer 13 has a concave groove 13a communicating with the end face from the inner circumference to the outer circumference, and the outer circumference has a groove 13a as shown in FIG.
Is formed between the sleeve 4 that supports the shaft 1 and the sleeve 12, thereby forming a gap that communicates with the gap 10. In this case, even if the concave groove 13a and the gap 10 do not directly communicate with each other, they communicate with each other through the C surface 13b.
The dynamic pressure generating oil interposed between the sleeve and the sleeve 4 or 12 can satisfactorily circulate between the upper and lower dynamic pressure bearings,
Thereby, the lubricating property of the dynamic pressure generating oil can be maintained and its deterioration can be suppressed.

FIG. 4 is an enlarged side view of the spacer 13 in FIG. The shape of the concave groove 13a communicating from the inner circumference to the outer circumference of the sleeve 13 can be changed to various shapes such as a round hole and a square hole.

[0016]

As described above, according to the present invention, a concave portion is formed in one or both of the outer peripheral surface of the sleeve and the inner peripheral surface of the bearing housing, and the concave portion is formed between the sleeve and the bearing housing. The gap in the axial direction formed by the insertion relationship between the two sleeves that support the rotating shaft, the spacer sandwiched between the two sleeves, on the surface in contact with the sleeve, provided with a recess connected from the inner circumference to the outer circumference, The gap and the spacer recess are communicated with each other to form a circulation path for the dynamic pressure generating oil, and the lubricating property of the dynamic pressure generating oil is maintained and its deterioration is suppressed, thereby greatly improving durability and reliability. Can be.

If a C-plane is formed on the outer periphery of the spacer, the gap can be communicated with the recess of the spacer by using the C-plane. The lubricity of the dynamic pressure generating oil can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spindle motor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a configuration of a circulation path of the dynamic pressure generating oil in FIG.

FIG. 3 is a sectional view taken on line AA of FIG. 2;

FIG. 4 is an enlarged view of a spacer 13 in FIG.

[Explanation of symbols]

 Reference Signs List 1 rotating shaft 1a dynamic pressure generating groove 2 stator base 3 bearing housing 3a key groove 4, 12 sleeve 5 core 6 coil 7 rotor 8 magnet 9 thrust plate 10 gap 13 spacer 13a concave portion 13b C surface

Claims (3)

[Claims] A dynamic pressure generating groove is formed on one of an outer peripheral surface of a shaft rotatably supported via two sleeves fixed inside a bearing housing or an inner peripheral surface of the sleeve, and In a motor bearing structure in which a dynamic pressure generating oil is interposed between the shaft and the sleeve, a concave portion is formed on one or both of an outer peripheral surface of the sleeve and an inner peripheral surface of the bearing housing. The recess provides an axial gap formed by the insertion relationship between the sleeve and the bearing housing, and between the two sleeves supporting the rotating shaft, at least one end face extends from the inner circumference to the outer circumference. A spacer having a recessed portion is provided, and the gap and the recessed portion of the spacer are communicated with each other to form a circulation passage for the dynamic pressure generating oil. A hydrodynamic bearing motor characterized in that: 2. The semiconductor device according to claim 1, further comprising two sleeves for supporting said rotary shaft, and a metal spacer sandwiched between said two sleeves and having a C-plane formed on at least one of adjacent outer peripheral surfaces. Item 2. The dynamic bearing motor according to Item 1. 3. The hydrodynamic bearing motor according to claim 1, wherein the spacer is made of a sintered metal or a resin.