JP2007211845A - Hydrodynamic bearing motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrodynamic bearing motor capable of attaining dimensional and processing accuracy, assembling accuracy and surface roughness by a common processing method such as surface grinding and having composition of parts easy to process a dynamic pressure generating groove. <P>SOLUTION: The hydrodynamic bearing motor has a stationary section which is formed of a base plate 2, a bearing body 4 engaged with the base plate, a pivot body 3 fitted in the bearing body and a central shaft 1 fixed at a lower end to the pivot body, and a rotary section which is formed of a sleeve 9 rotatably inserted in the central shaft and a thrust bearing 5 engaged with the sleeve. The thrust bearing is characterized in that it is held together with a limiter 7 between a cover 6 engaged with the bearing body and the pivot body, forms a dynamic pressure generating section P<SB>1</SB>in a radial direction between the central shaft and the sleeve and forms a dynamic pressure generating section P<SB>2</SB>, P<SB>3</SB>in a thrust direction between the thrust bearing, and the pivot body and the cover. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a small spindle motor having a fluid dynamic pressure bearing structure used for rotational driving of various OA devices, PDAs, other HDDs, etc., especially a hydrodynamic bearing motor intended for a microminiature motor of 1 inch or less. About.

  This type of small spindle motor has been required to be downsized at the same time as speeding up with the recent miniaturization of electronic equipment.

  Further, a hydrodynamic bearing motor of a center shaft fixed type has been known as compared with the shaft rotation type (see, for example, Patent Document 1 and Patent Document 2).

  An example of a small spindle motor will be described below with reference to FIG. FIG. 5 is an enlarged cross-sectional explanatory view of a main part of a spindle motor which is a hydrodynamic bearing motor (Japanese Patent Application No. 2004-239390) already filed by the present applicant, and the rotating portion is hatched.

  In FIG. 5, the thrust plate 104A provided at the lower portion is fixed to the lower portion of the rotary cylinder portion A, and the lower facing surface of the thrust plate 104A faces the facing surface of the dynamic pressure oil sealing plate 108A. The dynamic pressure oil sealing plate 108A is firmly engaged with the central shaft 101 via a stepped portion 101b in which the lower end of the base end 101a of the central shaft 101 is made smaller in diameter.

Then, the inner peripheral wall 115a of the bearing member 115, thereby forming a rotating cylindrical outer peripheral surface 116 and a dynamic pressure generating portion _{P 11} in the radial direction are opposed to the A of the hub 106.

Further, as described above the lower portion of the rotary cylinder portion A of the integral with the hub 106, the thrust plate 104A forming the dynamic pressure generating portion P ₁₂ opposite to the dynamic pressure oil sealing plate 108A of the surface is fixed integrally There Te, is the dynamic pressure generating portion P ₁₂ is configured to generate a thrust direction dynamic pressure. Also, the dynamic pressure generating portion P ₁₃ is formed in the bearing member 115 which faces the upper surface of the thrust plate 104A, has a configuration which also generates a thrust direction dynamic pressure.

The dynamic pressure generating portions P ₁₁ , P ₁₂ , and P ₁₃ in the radial direction and the thrust direction are filled with dynamic pressure oil, and a herringbone groove for generating dynamic pressure is formed.

  Reference numeral 110 is a rotor magnet, 111 is a stator, 112 is a disk, 113 is a disk fixing stopper, and 117 is a top cover screwed at the top of the central shaft 101.

In this spindle motor, a hub that rotates about a central axis 101, a dynamic pressure generating part P ₁₁ between the rotating cylindrical portion A and the bearing member 115, the thrust plate 104A and a lower dynamic pressure oil sealing plate 108A and Since dynamic pressures in the radial direction and the thrust direction are generated at the three locations of the dynamic pressure generating portions P ₁₂ and P ₁₃ with the upper bearing body 115, high-speed rotation can be achieved.
JP 2001-327125 A JP 2003-153484 A

  However, with the configuration of the small spindle motor as described above, it is difficult to obtain the processing accuracy and assembly accuracy of the parts. For example, the angle X in FIG. 5 requires a high-precision squareness, and the dimension Y requires a submicron machining accuracy. However, since the bearing body 115 is an integral part, automatic lathe machining is performed. The required processing accuracy cannot be obtained. Furthermore, a dynamic pressure generating groove must be formed on the surface of a part constituting the dynamic pressure generating portion. However, in the motor configuration as described above, the processing of the dynamic pressure generating groove is very difficult. This also leads to an increase in the production cost of the spindle motor.

  Furthermore, when the base end 101a and the dynamic pressure oil sealing plate 108A are joined by caulking, welding, adhesion, or the like, it is difficult to obtain good assembly accuracy.

  The present invention solves such problems, and provides a fluid dynamic bearing motor having a component structure that can provide dimensional processing accuracy, assembly accuracy, and surface roughness by a general processing method such as surface grinding, and can easily process a dynamic pressure generating groove. The purpose is to provide.

  In order to achieve the above-mentioned object, the present invention comprises the following configurations (1) to (3).

(1) A fixed portion composed of a substrate, a bearing body engaged with the substrate, a shaft support body fitted to the bearing body, and a central shaft having a lower end fixed to the shaft support body,
In a hydrodynamic bearing motor comprising: a sleeve rotatably inserted into the central shaft; and a rotating portion configured by a thrust bearing engaged with the sleeve.
The thrust bearing is sandwiched with a limiter between a cover engaged with the bearing body and the shaft support,
Forming a dynamic pressure generating portion in the radial direction between the central shaft and the sleeve, and forming a dynamic pressure generating portion in the thrust direction between the thrust bearing and the shaft support and the cover;
A fluid dynamic bearing motor.

(2) The engagement between the substrate and the bearing body, the engagement between the sleeve and the thrust bearing, and the engagement between the bearing body and the cover,
Made by inserting a retaining ring,
The hydrodynamic bearing motor according to (1) above, wherein

(3) A screw is provided at a lower end of the central shaft, and the central shaft is screwed to the shaft support body with a constant torque.
The hydrodynamic bearing motor according to (1) or (2) above, wherein

  Since the present invention has the above-described configuration, the component parts can be formed into a simple shape, and processing accuracy and assembly accuracy of the components can be easily obtained by means such as grinding and lapping. Further, by inserting a retaining ring having a spring property into a space having a slope formed by two parts, the two parts can be fixed without a gap without applying excessive force. Furthermore, by using the retaining ring in combination with an adhesive, it is possible to obtain a stable joint that also serves as an oil seal, and therefore it is possible to provide a fluid bearing motor that has good rotation and is inexpensive. Become.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  FIG. 1 is an enlarged cross-sectional explanatory view of a main part of a spindle motor which is a fluid dynamic bearing motor according to the present invention. A hatched portion indicates a rotating portion.

  In this figure, reference numeral 1 denotes a central axis (spindle), and a base end 1a thereof is screwed to a disk-shaped shaft support 3 having a screw shape. When this screw is fastened, the fastening torque is managed constant. This is to obtain the assembly accuracy of the entire spindle motor. An example of a central axis having a screw-shaped base end is shown in FIG.

  The shaft body 3 is engaged with the bearing body 4 by a stop ring 20, and the bearing body 4 is further engaged with the base 2.

  A thrust bearing 5 is installed on the upper surface of the shaft support 3, and the vertical direction of the shaft support 3 and the cover 6 is restricted. The distance between the shaft support 3 and the cover 6 is kept constant by the limiter 7. Further, the cover 6 and the bearing body 4 are also engaged by the retaining ring 20.

  The thrust bearing 5 is engaged with the sleeve 9 by a retaining ring 20, and the sleeve 9 is fitted and fixed to the hub 8. The sleeve 9 is inserted into the outer periphery of the central shaft 1 and rotates around the central shaft. The effect of using the retaining ring 20 will be described later.

  The upper outer peripheral surface of the hub 8 has a screw structure and is fastened to the clamp nut 15 by screws. The disk 12 placed on the hub 8 is fixed to the hub 8 by a clamp nut 15 via a clamp rubber 13 and a clamp plate 14.

  Reference numeral 10 denotes a magnet provided on the hub 8, and 11 denotes a stator. Reference numeral 16 denotes a top cover which is screwed to the central shaft on the upper surface of the central shaft 1.

  Although the illustrated example shows the inner rotor type in which the magnet 10 is on the inner side with respect to the stator 11, the same can be applied to an outer rotor type formed in the opposite direction.

In the structure According to the process 30, the sleeve 9 generates a radial dynamic pressure at the center axis 1 and the dynamic pressure generating portion P _1. The thrust bearing 5 has a dynamic pressure generating portion P ₂ between its upper surface and the lower surface of the cover 6, and a dynamic pressure generating portion P ₃ between its lower surface and the upper surface of the shaft support 3. Generate pressure. These dynamic pressure generating portions P ₁ , P ₂ , and P ₃ are filled with dynamic pressure generating oil to generate dynamic pressure, and for example, herringbone grooves are recessed in at least one surface (see FIG. 4). ).

  Here, the effect of using the retaining ring 20 will be described below.

  When parts are divided individually as in the present invention, joining between the parts is an important factor. As a method for joining the components of the spindle small motor according to the present invention, bonding, caulking, press-fitting, and welding can be considered.

  However, in the case of bonding, it is difficult to secure the bonding strength with an ultra-small and thin spindle motor because the bonding area is not sufficient. Further, in the caulking and press-fitting, a stress is generated in the component, so that deformation occurs, and there is a problem that assembly accuracy cannot be obtained. Furthermore, when welding is employed, thermal deformation occurs and assembly accuracy cannot be obtained.

  In the present invention, the stop ring 20 is used for such a situation. As shown in FIG. 2, by inserting a spring-like ring on a slope formed by two parts, it is possible to fix the two parts without gaps without applying excessive force. Further, by using it together with an adhesive also serving as an oil seal, a more stable joining configuration can be obtained.

  In FIG. 2, even if an impact load is applied in the J direction and the K direction, a force is applied to the retaining ring 20 in the direction of increasing the diameter, and the sandwiched parts can be more firmly fixed. The stop ring is formed larger than the groove diameter. An example of the stop ring 20 is shown in FIG.

  By having the above-described configuration, the spindle motor which is the fluid dynamic bearing motor of the present invention can accurately process its constituent parts by a general processing method, and can easily assemble the dynamic pressure generating groove. It becomes. Further, the use of the retaining ring enables the main components to be reliably connected without impairing accuracy.

It is an expanded sectional explanatory view of the important section of the fluid dynamic bearing motor concerning the present invention. It is a figure for demonstrating the stop ring used for the hydrodynamic bearing motor which concerns on this invention. It is a figure which shows an example of the stop ring used for this invention. It is a figure which shows an example of the center axis | shaft used for this invention. It is expansion sectional explanatory drawing of the principal part of the fluid bearing motor which concerns on the invention for which it applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Center shaft 1a Base end 2 Board | substrate 3 Shaft support body 4 Bearing body 5 Thrust bearing 6 Cover 7 Limiter 8 Hub 9 Sleeve 10 Magnet 11 Stator 12 Disc 13 Clamp rubber 14 Clamp plate 15 Clamp nut 16 Top cover 20 Stop ring 101 Center shaft 101a Base end 101b Step 104A Thrust plate 104a Locking hole 106 Hub 108A Dynamic pressure oil sealing plate 110 Rotor magnet 111 Stator 112 Disk 113 Stopper 115 Bearing body 115a Inner peripheral wall 116 Outer peripheral surface 117 Top cover P ₁ , P ₂ , P ₃ dynamic pressure generating part P ₁₁ , P ₁₂ , P ₁₃ dynamic pressure generating part A rotating cylinder part

Claims (3)

A fixed portion composed of a substrate, a bearing body engaged with the substrate, a shaft support body fitted to the bearing body, and a central shaft having a lower end fixed to the shaft support body;
In a hydrodynamic bearing motor comprising: a sleeve rotatably inserted into the central shaft; and a rotating portion configured by a thrust bearing engaged with the sleeve.
The thrust bearing is sandwiched with a limiter between a cover engaged with the bearing body and the shaft support,
Forming a dynamic pressure generating portion in the radial direction between the central shaft and the sleeve, and forming a dynamic pressure generating portion in the thrust direction between the thrust bearing and the shaft support and the cover;
A fluid dynamic bearing motor. The engagement between the substrate and the bearing body, the engagement between the sleeve and the thrust bearing, and the engagement between the bearing body and the cover,
Made by inserting a retaining ring,
The hydrodynamic bearing motor according to claim 1. A screw is provided at the lower end of the central shaft, and the central shaft is screwed to the shaft support body with a constant torque.
3. The hydrodynamic bearing motor according to claim 1, wherein the hydrodynamic bearing motor is provided.

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