WO2003073585A1

WO2003073585A1 - Motor

Info

Publication number: WO2003073585A1
Application number: PCT/JP2003/002316
Authority: WO
Inventors: Masaki Goto; Yoshimi Takasu
Original assignee: Sankyo Seiki Mfg. Co., Ltd.
Priority date: 2002-02-28
Filing date: 2003-02-28
Publication date: 2003-09-04
Also published as: JP2003259599A

Abstract

A motor, comprising a rotating shaft (4) formed in a hollow cylindrical shape, wherein at least the axial one end part of the rotating shaft (4) where deformed parts such as burrs and dents are liable to occur in manufacturing is positioned on the outside of the bearing face of a radial bearing part (RB) provided on a bearing member (3) so that, even if the deformed parts such as burrs and dents occur on the rotating shaft (4), the rotating shaft can be rotated satisfactorily without providing a damage to the bearing face of the radial bearing part (RB), whereby the rotating shaft (4) formed in the hollow cylindrical shape can be pivotally supported satisfactorily by a simple and low cost structure.

Description

Description Motor Technical field

The present invention relates to a motor having a hollow cylindrical rotary shaft. Background art

Generally, the rotating shaft of the motor is rotatably supported by an appropriate bearing member provided on the stay portion, and the entire rotor is integrally rotated with the rotating shaft. ing. In such a motor, proposals have been made in which the rotating shaft is formed of a hollow cylindrical member (see, for example, Japanese Patent Application Laid-Open No. 07-210130). If a rotating shaft made of hollow cylindrical member is adopted, it is possible to reduce the manufacturing cost drastically, reduce the weight of the rotating shaft and make the motor compatible with high-speed rotation, and improve heat dissipation. Advantages such as higher rotational accuracy and longer life of the motor can be obtained.

However, when manufacturing a rotating shaft using the hollow cylindrical member as described above, there is a problem that a deformed portion such as a burr dent or the like is likely to occur at the axial end during molding. In other words, if various deformed parts formed on the rotating shaft during molding continue to rotate within the bearing surface, the life of the bearing part will be markedly impaired, and it will cause galling and seizure. It could be.

Accordingly, an object of the present invention is to provide a motor capable of favorably supporting a hollow cylindrical rotary shaft with a simple and inexpensive configuration. Disclosure of the invention

In order to achieve the above object, in the invention according to claim 1, at least one end in the axial direction of the rotary shaft formed in a hollow cylindrical shape has an axial end position on a bearing surface provided on the radial bearing portion. It is arranged so as to be located more outward in the axial direction.

According to the motor according to claim 1 having such a configuration, the axial end of the rotating shaft where deformation parts such as burrs and dents are likely to occur is located outside the bearing surface. However, good rotation can be performed without the deformed portions damaging the bearing surface. With a simple and inexpensive configuration, the hollow cylindrical rotating shaft can be favorably supported, and the reliability of the motor can be improved. Performance can be improved.

Further, according to the motor described in claim 2, the rotating shaft according to claim 1 has a bottomed cylinder in which an opening is formed at one end in the axial direction and a bottom is formed at the other end in the axial direction. Since the end surface of one end in the axial direction of the rotating shaft having the opening is formed at a position protruding outward in the axial direction from the bearing surface of the radial bearing portion. In addition, the hollow cylindrical rotating shaft is easily formed by drawing or the like, so that productivity can be improved in addition to the effects described above.

Further, in the motor according to claim 3, a sealing cap member for closing the opening is fitted into the opening of the rotating shaft according to claim 2, and the rotating shaft is closed by the sealing cap member. Since the thrust bearing portion configured to support in the axial direction is configured, the thrust bearing portion is configured at low cost by the sealing cap member, and the productivity can be further improved in addition to the above-described effects.

Furthermore, in the mode described in claim 4, the sealing cap described in claim 3 is provided. Since the vent member has a through hole communicating with the inside and outside of the rotating shaft, even if air expansion occurs in the hollow cylindrical rotating shaft due to a rise in the operating environment temperature, the vent hole As a result, the deformation of the rotating shaft is prevented, and in addition to the effects described above, the thrust bearing can be configured at a low cost, and the reliability is further improved. Can be done.

Further, in the motor according to the fifth aspect, the vent hole according to the fourth aspect is formed by using one end surface in the axial direction or the inner peripheral wall that defines the opening of the rotating shaft. Ventilation holes are easily formed, and in addition to the effects described above, productivity can be further increased. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory longitudinal sectional view showing an embodiment of a polygon mirror-driving module of an optical deflecting device according to the present invention.

FIG. 2 is an external perspective explanatory view showing a structure of a sealing cap member fitted to the rotating shaft of the motor shown in FIG.

FIG. 3 is an explanatory longitudinal sectional view showing another embodiment of the polygon mirror driving motor of the optical deflection device according to the present invention.

FIG. 4 is an explanatory longitudinal sectional view showing still another embodiment of a polygon mirror driving motor of the optical deflection device according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to that, an example of the structure of a polygon mirror driving module in an optical deflector to which the present invention is applied will be described.

As shown in Fig. 1, the circuit board 1 also serves as a printed circuit board. A substantially hollow cylindrical bearing holder 12 is attached to the substantially central portion so as to stand upright, and a fixed bearing member using air dynamic pressure is provided on the inner peripheral wall surface of the bearing holder 2. Bearing sleeve 3 is bonded by bonding, light press fitting or shrink fitting. The bearing sleeve 3 is made of a hollow cylindrical member formed of a copper-based material such as phosphor bronze to facilitate small-diameter drilling and the like. The rotating shaft 4 constituting the overnight part is rotatably inserted. The structure of the rotating shaft 4 will be described later.

The dynamic pressure surface formed on the inner peripheral wall portion of the bearing sleeve 3 is disposed so as to face a dynamic pressure surface formed on the outer peripheral wall surface of the rotary shaft 4 via a minute gap in a radial direction. A radial dynamic pressure bearing portion RB is formed in the minute gap. That is, in the radial dynamic pressure bearing portion RB, the dynamic pressure surface on the bearing sleeve 3 side and the dynamic pressure surface on the rotating shaft 4 side are circumferentially opposed to each other with a small gap of several m. Air as lubricating fluid is interposed in the bearing space consisting of the minute gap.

At least one of the two dynamic pressure surfaces of the bearing sleeve 3 and the rotating shaft 4 is provided with a radial dynamic pressure generating groove having an appropriate groove shape so as to be annularly arranged in parallel. During rotation, the air as the lubricating fluid is pressurized by the bombing action of the radial dynamic pressure generating groove to generate a dynamic pressure, and the dynamic pressure of the air as the lubricating fluid causes the air and the rotating shaft 4 to rotate together. A rotor case 5 described later is configured to be axially supported by the bearing sleeve 3 in a non-contact state in a radial direction.

On the other hand, at a portion where the bearing holder 12 protrudes upward from the motor board 1 toward the upper side in the figure, a stator core 6 made of a laminated body of electromagnetic steel sheets is mounted on the outer peripheral side of the bearing holder 2. Surface and fitted radially outward at the stay core 6. A coil winding 7 is wound around each of a plurality of salient pole portions provided so as to project radially.

Further, a stepped cylindrical mouth boss 8 formed of an aluminum alloy is provided at an output portion where the rotary shaft 4 projects upward from the bearing sleeve 3 toward the upper side in the figure, with respect to the rotary shaft 4. It is fixed through a press-fit or shrink-fitting process. On the lower surface side of the illustrated boss 8 in the figure, the central portion of the roughly illustrated case 5 is fixed by caulking or the like.

A ring-shaped magnet 9 is mounted on the inner peripheral wall surface of the annular wall 5 a provided on the outer peripheral portion of the rotor case 5. The inner peripheral wall surface of the mouth tag net 9 is arranged so as to be radially opposed to the outer end surface of each salient pole portion of the stay core 6 described above.

On the other hand, a mounting portion 8a formed in a step shape is formed on the outer peripheral portion of the above-described row boss 8, and deflection scanning of optical information is performed on the step portion of the mounting portion 8a. It is mounted so that a polygon mirror 1 1 is placed on it. The polygon mirror is fixed by being pressed in the axial direction by a plate-shaped holding member 12 attached to the upper end surface (bottom portion 4b) of the rotary shaft 4 in the figure by a fixing screw 11a. Have been.

Here, the above-mentioned rotary shaft 4 is formed by forming a stainless steel material into a hollow cylindrical shape with a bottom, and has an opening 4a formed at one end on the lower end side in the axial direction as shown in FIG. A bottom 4b is formed at the other end of the upper end in the drawing. As described above, the fixing screw 11a is screwed to the bottom 4b of the rotating shaft 4 at the upper end in the drawing so as to penetrate along the center of the shaft.

Further, one end face of the rotating shaft 4 at the lower end in the drawing, that is, the annular end face at the one end where the opening 4a is formed is the radial bearing part described above. It is located at a position slightly protruding axially outward (downward in the figure) from the bearing surface of the RB. More specifically, with respect to the dynamic pressure surface of the bearing sleeve 3 constituting the bearing surface of the above-described radial bearing portion RB, the lower end side edge of the dynamic pressure surface of the bearing sleeve 3 in FIG. , The axial position “B” of the illustrated lower end surface of the rotating shaft 4 is slightly outwardly below the illustrated lower end position “A” of the dynamic pressure surface of the bearing sleeve 3. It is arranged to be located. Thus, the lower end of the rotating shaft 4 in the figure is prevented from rotating in the bearing surface of the radial bearing portion RB.

Further, a sealing cap member 13 made of resin or the like is fitted into the opening 4a on the lower end in the figure of the rotating shaft 4 so as to close the opening 4a. The sealing cap member 13 is formed so as to have a substantially hemispherical surface shape from the opening 4 a of the rotating shaft 4 and protrude downward in the drawing, and has a substantially hemispherical surface shape. By contacting the top of the thrust plate 14 with a disc-shaped thrust plate 14, a pivot-shaped thrust bearing SB is formed. At this time, the thrust plate 14 is attached so as to close the opening at the lower end in the drawing of the bearing holder 12 described above.

The sealing cap member 13 has a ventilation hole 13 a communicating therewith between the inside and outside of the rotating shaft 4. The ventilation hole 13a in the present embodiment is formed by cutting out a part of the sealing cap member 13. That is, utilizing the lower end portion of the rotary shaft 4 defining the opening 4a of the rotary shaft 4, a wall surface extending from the inner peripheral wall surface to the lower end surface of the rotary shaft 4 at the lower end portion of the rotary shaft 4 shown in FIG. The passage of the ventilation hole 13 a is defined between the notch of the sealing cap member 13 and the notch.

According to the motor according to the present embodiment, in manufacturing the bottomed cylindrical rotating shaft 4, the rotating shaft 4 in which deformed portions such as burrs and dents are likely to occur is produced. Since one end of the rotating shaft 4 (the opening 4a at the lower end in the figure) is located outside the bearing surface of the radial bearing RB, the deformed portion of the rotating shaft 4 is The bearing surface is not damaged, and good rotation is continued.

At this time, since the rotating shaft 4 according to the present embodiment described above is formed in a bottomed cylindrical shape, it is easily formed by drawing or the like.

Further, in the module according to the present embodiment, the sealing cap member 13 that closes the opening 4a is fitted into the opening 4a on the lower end side of the rotary shaft 4 in the figure. The thrust bearing SB can be configured at low cost. Furthermore, since the ventilation hole 13a is formed through the sealing cap member 13, air expansion occurs in the hollow cylindrical rotary shaft 4 due to an increase in the operating environment temperature. Even so, air is vented through the ventilation holes 13a of the sealing cap member 13 to prevent the rotation shaft 4 from being deformed.

At this time, the sealing cap member 13 is provided with a longitudinal groove 13b as shown in FIG. 2 (a) or an annular groove 1b as shown in FIG. 2 (b).

If 3c is provided, and the adhesive for fixing is injected into each of the grooves 13b, 13c, the sealing cap member 13 can be fixed. It will be performed well.

In addition, the vent hole 13 a in the above-described embodiment is an opening of the rotating shaft 4.

Since it is formed using the one end surface in the axial direction and the inner peripheral wall defining 4a, the formation of the ventilation hole 13a is facilitated. Further, in the motor according to FIGS. 3 and 4 in which members corresponding to the above-described embodiment are represented by the same reference numerals, the thrust bearing portion SB provided on the lower end in the drawing of the rotating shaft 4 is connected to the rotating shaft 4 side. And the magnetic reluctance of the annular magnets M 1 and M 2 attached to the bearing holder 2 side in the radial direction It is configured using the power. In the embodiment in which the thrust bearing portion is formed by such a magnet, the same operation and effect as those in the above-described embodiment can be obtained.

In the embodiment shown in FIG. 4, since the annular magnet M1 is directly attached to the rotating shaft 4, the rotating shaft 4 is made of a non-magnetic stainless steel or the like. Is formed.

As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and can be variously modified without departing from the gist thereof. Needless to say. For example, in each of the above-described embodiments, the present invention is applied to a polygon mirror driving module. However, the present invention is applied to other types of hard disk driving module and optical disk driving module. However, the present invention can be similarly applied.

Further, in each of the above embodiments, the air dynamic pressure bearing is described as the radial bearing, but a sliding bearing such as an oil dynamic pressure bearing / a sintered oil-impregnated bearing may be used. Industrial applicability

As described above, the motor according to the present invention is particularly useful in a motor corresponding to a high-speed rotation, but can be variously modified without departing from the gist thereof, and can be used in various types. It can be suitably used for morning and evening.

Claims

The scope of the claims

1. A rotor portion having a rotating shaft formed in a hollow cylindrical shape, and a stay portion provided with a radial bearing portion having a bearing surface for rotatably supporting the rotating shaft,

At least one end in the axial direction of the rotating shaft is disposed so as to be located axially outward of an axial end position on a bearing surface provided on the radial bearing portion. Morning evening.

2. The rotating shaft is configured to have a bottomed cylindrical shape in which an opening is formed at one axial end and a bottom is formed at the other axial end, and the opening is formed. 2. The motor according to claim 1, wherein an end surface of one end in the axial direction of the rotating shaft is disposed at a position protruding outward in the axial direction from a bearing surface of the radial bearing portion.

3. A sealing cap member for closing the opening is fitted into the opening of the rotating shaft,

3. The motor according to claim 2, wherein the sealing cap member forms a thrust bearing portion that supports the rotating shaft in the axial direction.

4. The motor according to claim 3, wherein a ventilation hole communicating between the inside and outside of the rotating shaft is formed through the sealing cap member.

5. The motor according to claim 4, wherein the ventilation hole is formed by using one axial end surface or an inner peripheral wall defining an opening of the rotating shaft.