JPH08205439A - Motor - Google Patents

Abstract

PURPOSE: To obtain a small-sized and high speed motor in which heat dissipation of the coil is enhanced through a simple and low cost structure. CONSTITUTION: The space A in the rotor arranged with a drive coil 24 is communicated through a through hole 40 with the outer space B of rotor side where a negative pressure is generated through rotation of a rotary board 34. The air on the inner space side of the drive coil 24 is made to flow through the cooling hole 40 toward the negative pressure space on the outside of the rotary board 34 thus cooling and heat dissipation of the drive coil 24 are performed well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor for rotating a predetermined rotary plate.

[0002]

2. Description of the Related Art In recent years, polygon mirrors, magnetic disks,
Various proposals have been made for motors for rotating various rotary plates such as optical disks. As an example thereof, the basic structure of a motor having the air dynamic pressure bearing shown in FIG. 1 will be described. Although FIG. 1 shows a motor according to the present invention, since the basic structure of a conventional motor is also the same, description will be given based on this drawing.

That is, FIG. 1 shows an example of an air dynamic bearing type outer rotor type motor for rotationally driving a polygon mirror, and a stator set 2 as a fixed member assembled to the frame 1 side, A rotor set 3 as a rotating member is attached to the stator set 2 so as to be fitted from above in the drawing.
Of these, the stator set 2 has a fixed shaft 21 which is erected at a substantially central position of the frame 1, and a bearing holder 22 which surrounds the fixed shaft 21 in a cylindrical shape at a constant distance from the outer peripheral surface thereof. A stator core 23 is fitted on the outer circumference of the bearing holder 22. A drive coil 24 is wound around the salient pole portion of the stator core 23.

On the outer peripheral surface of the fixed shaft 21, a herringbone type dynamic pressure generating groove 25 is axially divided into two blocks and annularly recessed, and the dynamic pressure generating groove 2 is provided.
The cylindrical body 31 of the rotor set 3 is rotatably mounted on the outer side of the fixed shaft 21 on which the rotors 5, 25 are provided. Further, a dynamic pressure is generated between the outer peripheral surface of the fixed shaft 21 and the inner peripheral surface of the cylindrical body portion 31 of the rotor set 3 to form a radial bearing. Further, an air supply hole 26 extends in the axial direction from the shaft end portion (upper end portion in the drawing) of the fixed shaft 21, and the air supply hole 26 generates the dynamic pressure of the two blocks. Groove 2
The portion between 5 and 25 is open toward the outside of the fixed shaft 21.

Further, the shaft end portion (upper end portion in the drawing) of the fixed shaft 21 has an outer edge portion protruding in the axial direction by a predetermined amount, and a fixed side magnet 27 for thrust levitation is annularly formed on the inner peripheral wall of the protruding portion. It is installed. On the other hand, on the base side (upper end side in the drawing) of the cylindrical body portion 31 of the rotor set 3, a fine air orifice 32 having a predetermined air flow resistance is axially formed through the central portion thereof. , By the damper action of the air orifice 32, the rotor assembly 3
Axial impact on the is reduced.
Further, the air inside the rotor set 3 is fed to the portion between the dynamic pressure generating grooves 25, 25 by the air supply hole 26, and the pumping action of the dynamic pressure generating grooves 25, 25 causes the air pressure in the axially outer direction in the vertical direction in the figure. And is discharged to the outside.

In addition, around the air orifice 32,
A rotation-side magnet 33 for floating the thrust is attached in an annular shape. The rotating-side magnet 33 is magnetized in the axial direction (the vertical direction in the drawing) so as to mutually generate a magnetic attractive force with the fixed-side magnet 27 on the fixed shaft 21 side. The set 3 is configured to be held in a state of being floated by a predetermined amount in the thrust direction.

On the other hand, the base side (shown upper end) outer periphery of the cylindrical body portion 31 of the rotor assembly 3 is a plan hexagonal polygon mirror 34 serving as a rotary plate is fitted. The polygon mirror 34 is axially mounted on a holding portion 38 extending outward from the cylindrical body portion 31, and is fixed by a holding spring 39 which is a clamping means.

A rotor flange portion 35 extends radially outward from the holding portion 38. The rotor flange portion 35 is composed of a disk-shaped member integrally formed with the cylindrical body portion 31 and the holding portion 38. The rotor flange portion 35 is provided between the drive coil 24 and the polygon mirror 34 at a portion between the two members 24, 34. It is arranged to face each other with a space in between. That is, this rotor flange portion 3
5 is arranged so as to partition the rotor inner space in which the drive coil 24 is arranged and the rotor outer space in which the polygon mirror 34 is arranged.

Further, a drive magnet 37 is annularly mounted on an inner peripheral wall surface of an annular mounting plate 36 projecting from the outer peripheral portion of the rotor flange portion 35 in the axial direction (downward direction in the drawing) via a back yoke made of a magnetic material. Is attached to. The drive magnet 37 is arranged so as to face the outer peripheral surface of the stator core 23 described above in the radial direction.

In FIG. 1, the holding portion 38 and the cylindrical body portion 3 are shown.
1, the rotor flange portion 35 and the mounting portion 36 are integrally formed, but they may be formed separately.

[0011]

In recent years, in motors for rotationally driving a rotary plate such as a polygon mirror, there has been a strong demand for high-speed rotation and miniaturization, and accordingly, the temperature generated in the motor is increased. Is increasing year by year. However, since the supply of drive current is limited to suppress the temperature of the coil, how to lower the temperature inside the motor, that is, how to increase the cooling and heat dissipation of the coil determines high-speed rotation and miniaturization of the motor. In some cases.

Therefore, an object of the present invention is to provide a motor capable of sufficiently increasing the amount of heat radiation from the coil with a simple and low-cost structure.

[0013]

In order to achieve the above object, the first means and the second means of the present invention are a stator having a drive coil, a rotor having a drive magnet arranged to face the stator, and the rotor. A rotor flange extending in the radial direction at a portion between the drive coil and the rotary plate, with an axial space between the drive coil and the rotary plate. In the motor having a portion, the rotor flange portion has a configuration in which a through hole is formed for communicating the rotor inner space in which the drive coil is arranged with the rotor outer space where negative pressure is generated by rotation of the rotating plate. ing.

In addition to the structure of the above-mentioned first means, the third means of the present invention is such that, in the opening of the through hole to the inner space of the rotor, the edge portion located on the upstream side in the rotation direction of the rotating plate has an axial direction. It has a configuration in which a protruding portion that stands upright is attached.

Further, in addition to the structure of the above-mentioned first means, the fourth means of the present invention is characterized in that the opening of the through hole to the rotor inner space is
It has a structure in which a chamfered portion is formed on the inner wall surface located on the downstream side in the rotation direction of the rotating plate.

Still further, a fifth means of the present invention is the above first
In addition to the configuration of the means or the second means, the through hole has a configuration that extends so as to incline from the rotor inner space side toward the rotation direction downstream side of the rotating plate and is opened to the rotor outer space. .

Furthermore, the sixth means of the present invention is based on the first aspect.
In addition to the structure of the means, the rotor is rotatably supported via an air dynamic pressure bearing, and the air dynamic pressure bearing allows the air inside the bearing to flow axially to the outside space side. It has a structure in which a dynamic pressure generating groove for discharging is provided.

[0018]

In the first means and the second means according to the present invention, the air in the rotor inner space passes through the through hole provided in the rotor flange portion by the negative pressure generated by the rotation of the rotating plate in the rotor outer space. The drive coil is directly cooled by the flowing air that is sucked and discharged to the rotor outer space side, and the heat generated from the drive coil is also
Similarly, heat is satisfactorily radiated to the space outside the rotor through the through holes.

Further, in the third means and the fourth means of the present invention, the air in the rotor inner space is well guided into the through hole, and the cooling and heat radiating action in the first means and the second means. It is being improved.

Further, in the fifth means of the present invention, the negative pressure due to the rotation of the rotary plate is favorably applied to the through hole, and the cooling and heat radiating action in the first means and the second means is further enhanced. It is being improved.

Further, in the sixth means of the present invention, the flow of the cooling air in the first means coincides with the flow of the dynamic pressure air by the air dynamic pressure bearing, and the flow of the cooling air is favorably promoted. It is supposed to be done.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings. The overall structure of the motor shown in FIG. 1, which represents an embodiment of the present invention, has already been described in the section of the prior art, and therefore will be omitted, and the main part of the present invention will be described below.

First, as shown in FIG. 2, a polygon mirror 34 as a rotating plate is axially fitted to the holding portion 38 of the cylindrical body portion 31 of the rotor set 3, and the holding portion 38 is provided. From, a rotor flange portion 35 extends outward in the radial direction. This rotor flange 3
Reference numeral 5 denotes a disk-shaped member integrally formed with the cylindrical body portion 31 and the holding portion 38, and extends in a portion between the drive coil 24 and the polygon mirror 34.
4 are arranged so as to face each other with a space in the axial direction.

That is, the space inside and outside the rotor is partitioned by the substantially cup-shaped member formed by the rotor flange portion 35 and the above-mentioned mounting plate 36, and the rotor internal space A in which the drive coil 24 is arranged, A rotor outer space B in which the polygon mirror 34 is arranged is defined.

As shown in FIG. 3, a plurality of through holes 40 are formed in the rotor flange portion 35 in the axial direction. Each of these through holes 40 is opened in the rotor inner space A and the rotor outer space B, and the through hole 40 is configured so that the rotor inner space A and the rotor outer space B communicate with each other. There is.

At this time, the outer space B of the rotor is made a negative pressure by the rotation of the polygon mirror 34. That is, the air in the vicinity of the rotating plate-like object is dragged by the plate-like object and rotates, and the centrifugal force generated by the rotation causes the air to flow toward the outer peripheral side of the plate-like object. It becomes negative pressure. Therefore, the rotation of the polygon mirror 34 causes the outer space B of the rotor to become a negative pressure space, and the inner space A of the rotor in which the drive coil 24 is disposed.
Is communicated with the rotor outer space B as a negative pressure space through the through hole 40.

As described above, in the apparatus of this embodiment, the rotor inner space A in which the drive coil 24 is arranged and the rotor outer space B in which the negative pressure is generated by the rotation of the polygon mirror 34 are provided.
Since the through hole 40 communicates with the through hole 40, the air in the rotor internal space A is not connected to the through hole 4 as shown by the broken line in FIG.
Through 0, it is sucked and flows toward the rotor outer space B side which is a negative pressure space. Therefore, the drive coil 24 is directly cooled by the flow of the air and the drive coil 2 is also cooled.
The heat generated from No. 4 is also sucked and discharged to the outside negative pressure space side of the polygon mirror 34 through the through hole 40 together with the air, whereby the driving coil 24 is cooled and the heat is radiated favorably.

Further, in the present embodiment, the pumping action of the dynamic pressure generating grooves 25, 25 is configured to flow the air axially outward (vertical direction in the drawing) to discharge the air to the outside. The flow of the cooling air is promoted by the flow of the dynamic pressure air, so that the negative pressure suction action of the cooling air is more favorably performed.

Further, the through hole 50 in the embodiment shown in FIG. 4 is constructed so as to extend from the rotor internal space A side toward the downstream side in the rotation direction (right direction in the drawing) of the polygon mirror 34 in an inclined manner. The opening is formed so as to face the lower surface of the polygon mirror 34 in the rotor outer space B in the drawing.

According to the through hole 50 in such an embodiment, as shown by the broken line in FIG. 4, the air on the rotor internal space A side is well guided into the through hole 50. The cooling and heat dissipation action of the drive coil 24 described above is further improved.

On the other hand, the through hole 60 in the embodiment shown in FIG. 5 is provided so as to have the same inclination as in the embodiment according to FIG. A chamfered portion 60a is formed in a tapered shape on the inner wall surface of the opening located on the downstream side in the rotation direction of the polygon mirror 34.

The through hole 60 in such an embodiment also allows the air on the rotor internal space A side to be satisfactorily guided into the through hole 60, thus improving the cooling and heat radiating action of the drive coil 24 described above. .

Further, the through hole 70 in the embodiment shown in FIG. 6 is also provided so as to have the same inclination as in the embodiment according to FIGS. 4 and 5, and the space inside the rotor of the through hole 70 is also provided. A projection 71 standing upright in the axial direction is attached to the edge of the opening to A. This protrusion 71 is shown in FIG.
As also shown in FIG. 3, it is formed of a half-divided-angle air guide member mounted on the upstream side in the rotation direction (right direction in the drawing) of the polygon mirror 34.

Even with the through hole 70 in such an embodiment, as shown by the broken line in FIG.
The air on the side is favorably guided into the through hole 70, and the above-described cooling and heat dissipation action of the drive coil 24 is improved.

When such an air guide member is provided, as shown in FIGS. 8 and 9, a half-divided cylindrical projection 81 is provided in the through hole 80 extending in the axial direction. It can also be configured as follows.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, in order to rotationally drive a motor using a bearing other than an air dynamic pressure bearing such as a ball bearing or a sliding bearing, a shaft rotation type motor, and various rotary plates such as a magnetic disk and an optical disk other than a polygon mirror. The present invention can be similarly applied to the above motor. The present invention is also applicable to a face-to-face type coreless motor.

For example, for a shaft rotation type motor as shown in FIG. 10 in which members corresponding to FIG. 1 are represented by the same reference numerals, a yoke extending between the polygon mirror 34 and the stator core 23 is provided. The same action and effect can be obtained by forming the through hole 90 in the flange portion 35.

[0038]

As described above, in the motor according to the present invention, the inner space of the rotor, in which the drive coil is arranged, is connected to the outer space of the rotor where negative pressure is generated by the rotation of the rotary plate through the through hole to drive the motor. Air in the internal space on the coil side is made to flow through the through hole toward the external negative pressure space side on the rotating plate side to directly cool the drive coil, and at the same time, heat generated from the drive coil is transferred to the outside side through the through hole. Since it is configured to suck and discharge, and to perform good cooling and heat dissipation of the drive coil, it is possible to sufficiently increase the heat dissipation from the coil with a simple and low-cost structure.
It is possible to favorably achieve high-speed rotation and miniaturization of the motor.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional explanatory view showing an air dynamic bearing type motor according to an embodiment of the present invention.

FIG. 2 is a semi-longitudinal section explanatory view showing an enlarged main part of the present invention.

3 is a cross-sectional explanatory view taken along the line III-III in FIG.

FIG. 4 is a vertical cross-sectional explanatory view taken along the line IV-IV in FIG.

FIG. 5 is an explanatory longitudinal sectional view corresponding to FIG. 4 showing a through hole in another embodiment of the present invention.

FIG. 6 is a vertical cross-sectional explanatory view corresponding to FIG. 4 showing through holes and protrusions in still another embodiment of the present invention.

FIG. 7 is an external perspective explanatory view showing a protrusion in the embodiment of FIG.

FIG. 8 is an explanatory longitudinal sectional view corresponding to FIG. 4 showing through holes and protrusions in still another embodiment of the present invention.

9 is an external perspective view showing a protrusion in the embodiment of FIG.

FIG. 10 is a partial vertical cross-sectional explanatory view showing a motor of a shaft rotation type air dynamic pressure bearing showing another application example of the present invention.

[Explanation of symbols]

 21 fixed shaft 24 drive coil 25 dynamic pressure generating groove 31 rotor cylindrical body portion 34 polygon mirror 35 rotor flange portion 40, 50, 60, 70, 80 through hole 71, 81 protrusion

Claims (6)

[Claims] 1. A motor comprising: a stator having a drive coil; a rotor having a drive magnet arranged to face the stator; and a predetermined rotating plate mounted on the rotor, wherein the rotor has the drive A rotor flange portion that extends in the radial direction with a space in the axial direction is provided between the coil and the rotating plate, and the rotor flange portion has a rotor inner space in which the drive coil is arranged. A through hole that communicates with a rotor outer space where negative pressure is generated by rotation of the rotary plate. 2. The motor according to claim 1, wherein the rotor flange portion is provided so as to extend radially outward from a holding portion that holds the rotating plate. 3. The motor according to claim 1, wherein the opening of the through hole to the inner space of the rotor is provided with a protrusion that stands up in the axial direction at an edge portion that is located on the upstream side in the rotation direction of the rotating plate. A motor characterized by being installed. 4. The motor according to claim 1, wherein a chamfered portion is formed on an inner wall surface of the through hole, which is located on a downstream side in the rotation direction of the rotating plate, in the opening to the rotor inner space. And a motor. 5. The motor according to claim 1 or 2, wherein the through hole extends from the inner space side of the rotor so as to be inclined toward the downstream side in the rotation direction of the rotating plate, and is opened to the outer space of the rotor. A motor characterized by. 6. The motor according to claim 1, wherein the rotor is rotatably supported via an air dynamic pressure bearing, and the air inside the bearing flows axially in the air dynamic pressure bearing. A motor having a groove for generating dynamic pressure for discharging to the external space side.