JP2000060056A - Motor and rotary element device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized motor and a small-sized rotary element device which can stably rotate at a high speed. SOLUTION: A thrust bearing disc 21 made of magnetic material is fixed to a rotary shaft 10. A cylindrical radially anisotropic rotor magnet 31 is fixed coaxially to the outer circumference of the thrust bearing disc 21. A pair of axial direction electromagnets 22 are provided, so as to face each other with the thrust bearing disc 21 therebetween and the thrust bearing disc 21 is supported in the thrust direction by the axial direction force produced by the axial direction electromagnets 22. A plurality of stator coils 33 are provided on the outside in the radial direction of the rotor magnet 31. A rotary magnetic field is formed by the stator coils 33, and the rotor magnet 31 is energized to turn the thrust bearing disc 21 and the rotary shaft 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor and a rotating body device, and more particularly to a radial air gap type and inner rotor type motor and a rotating body device capable of miniaturization and high-speed rotation.

[0002]

2. Description of the Related Art Conventionally, radial air gap type motors have been widely known, for example, as spindle motors used in machine tools and the like, polygon mirrors and direct drive motors used in OA equipment and the like. It is used. FIG. 6 shows a DC motor supported by a magnetic bearing as an example of such a radial air gap type motor.

The radial air gap type motor shown in FIG. 6 is an inner rotor type DC motor, and a rotor portion R of the motor is fixed to a rotating shaft 10. The rotor section R has a rotor magnet 31 on the peripheral surface. A stator portion S is provided around the rotor portion R, and a stator coil 33 wound around an iron core is provided in the stator portion S so as to face the rotor magnet 31. Then, the stator coil 33 urges the rotor magnet 31 to rotate the rotor portion R and the rotating shaft 10. A disk-shaped thrust bearing disk 21 is coaxially fixed to the rotating shaft 10. The thrust bearing disk 21 is attracted by the axial electromagnets 22 from both sides in the thrust direction and is supported in the thrust direction. Although not shown, the rotary shaft 10 is further provided with a radial bearing closer to the end than the rotor portion R and the thrust bearing disk 21.

In recent years, there has been a demand for miniaturization of various devices and devices in recent years, and a motor used in such devices and devices has been required to be small and capable of rotating at high speed. As described above, a motor that supports a rotating shaft by a magnetic bearing or a motor that supports a rotating shaft by a dynamic pressure bearing or a static pressure bearing has a durability in which the bearing member on the rotor side and the bearing member on the stator side are not in contact with each other. It is suitable for high-speed rotation in that it is excellent in such a point that it can meet such a demand.

[0005]

However, in the motor of the prior art as described above, the rotating shaft 10 is provided with a thrust bearing member (thrust bearing disk 21), a radial bearing member, and a rotor portion R of the motor. Since each is fixed, the natural frequency of the rotating shaft 10 decreases, and the possible rotation speed may decrease. Also,
It is necessary to dispose a thrust bearing member (thrust bearing disc 21), a radial bearing member, and a rotor portion R of a motor on the rotating shaft 10, and a sufficient length is required for the rotating shaft. Therefore, miniaturization of the motor is limited. Further, since the load applied in the radial direction to the rotating shaft 10 is biased at the position in the thrust direction,
Conical motion may easily occur during rotation.
In order to reduce this drawback, a technique of arranging the thrust bearing portion at two locations in contrast to the rotor portion R can be considered. In this case, the above-mentioned possible reduction in the rotational speed is further reduced. It is also a factor that hinders downsizing of the motor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a small-sized motor and a rotating body device capable of rotating stably at high speed.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a rotating shaft, a projecting portion provided to project radially from the rotating shaft, Thrust bearing means arranged outward in the thrust direction to face the overhanging portion and supporting the overhanging portion in the thrust direction; a rotor portion disposed at an edge of the overhanging portion; and the rotor The object is achieved by providing a motor that is disposed radially outward of a portion and includes a stator member that urges the rotor portion to rotate the overhang portion and the rotation shaft in a direction around the axis thereof. I do.

In the motor of the present invention, the rotor is disposed at the edge of the overhang provided integrally with the rotary shaft, and the overhang is supported in the thrust direction by thrust bearing means. The rotor is rotated by the stator member. Therefore, since the rotor portion is not separately fixed to the rotating shaft, it is not necessary to provide a space for this on the rotating shaft,
The rotating shaft length can be set short, miniaturizing the motor,
The rotation speed can be prevented from lowering and the rotation can be stabilized. Further, since the rotor diameter is set large, it is possible to obtain a high output while being small.

The present invention achieves the above object by providing a rotating body device provided with the above-described motor of the present invention.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an axial cross-sectional view showing a schematic configuration of a motor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the motor of the present embodiment taken along line AA in FIG.

As shown in FIG. 1, the motor according to the present embodiment includes a rotating shaft 10, a thrust bearing portion 20 for supporting the rotating shaft 10 in a thrust direction, and a motor portion 30 for rotating the rotating shaft 10. Have. The thrust bearing portion 20 is provided with a thrust bearing disk 21 as a magnetic member.
, An axial electromagnet 22 for generating an axial magnetic force, and an axial sensor (not shown) for detecting an axial position of the rotating shaft 10.

As shown in FIG. 2, the thrust bearing disk 21 has a disk shape having a circular hole at the center. The rotating shaft 10 is inserted through the circular hole and fixed coaxially to the rotating shaft 10 so that the rotating shaft 10 rotates integrally with the rotating shaft 10. The axial electromagnet 22, as shown in FIG.
The thrust bearing disk 21 is interposed therebetween so as to be opposed to each other in the thrust direction so as to form a pair. It supports in the direction. This axial electromagnet 2
The excitation current of No. 2 is controlled according to a position detection signal from an axial sensor (not shown), whereby the rotating shaft 10 is held at a predetermined position in the axial direction.

As shown in FIG. 2, the motor unit 30 includes a cylindrical radially anisotropic rotor magnet 31 coaxially fixed to the outer periphery of the thrust bearing disk 21. A protective cover 32 is fitted to the rotor magnet 31 from outside. In addition, the motor unit 30 includes a plurality of stator coils 33 that face the rotor magnet 31 via the protective cover 32. A rotating magnetic field is formed by these stator coils 33, and the rotor magnet 31 is biased to thrust. The bearing disk 21 is rotated.

Further, although not shown, the motor of the present embodiment has a thrust bearing portion 2 as a radial bearing portion.
In contrast to the radial bearing sleeves, two radial bearing sleeves made of two cylindrical magnetic bodies fixed to the rotating shaft 10 and two pairs of the radial bearing sleeves are arranged vertically around each radial bearing sleeve to generate a radial magnetic force. And a radial electromagnet. Each radial bearing sleeve is supported in the radial direction by the radial magnetic force of the radial electromagnet. In the vicinity of each radial electromagnet, there is provided a radial sensor for detecting the position of the rotating shaft in the radial direction, and the exciting current of this radial electromagnet is
Control is performed in accordance with a position detection signal from a radial direction sensor (not shown), and the rotating shaft is held at a predetermined position in the radial direction.

According to the present embodiment, the rotor magnet 31 is fixed to the outer periphery of the thrust bearing disk 21 and the member for supporting the rotor magnet 31 is not fixed to the rotating shaft 10 independently. There is no need to provide a space, the rotating shaft length can be set short, and the size of the motor can be reduced. That is, since the thrust bearing disk 21 is also used as the motor rotor, the size of the motor can be reduced. According to the present embodiment, the thrust bearing disk 21
Since the rotor magnet 31 is fixed to the outer periphery of the shaft and the member supporting the rotor magnet 31 is not fixed to the rotating shaft 10, a decrease in the natural frequency of the rotating shaft 10 can be avoided, and a possible decrease in the rotating speed can be prevented. Can be.

According to the present embodiment, since the rotor magnet 31 is fixed to the outer periphery of the thrust bearing disk 21 and the position of the thrust bearing disk 21 matches the rotational drive position, conical motion of the rotary shaft 10 occurs. It becomes difficult, the rotation is stabilized, and the controllability is improved. According to the present embodiment, since the rotor magnet 31 is fixed to the outer periphery of the thrust bearing disk 21, the rotor diameter is set large, and high output can be obtained while being small. The motor output P is obtained by the following equation. P = k × d × d × l (k: constant, d: rotor diameter, l: rotor length)

Further, since it is possible to obtain a high output while being small in size, restrictions on other members and the like are relaxed, and design is facilitated. According to the present embodiment, the rotor magnet 31 is fixed to the outer periphery of the thrust bearing disk 21, and a unique member for supporting the rotor magnet 31 is not required.
Production costs can be kept low, and assemblability is improved.

Next, an embodiment of the rotating body device of the present invention will be described. FIG. 3 is an explanatory diagram showing a schematic configuration of a machining center as one embodiment of the rotating body device of the present invention. As shown in FIG. 3, the machining center according to the present embodiment includes a work table 51 on which a workpiece W is placed and which can move horizontally, and a support table 52 which can move vertically with respect to the work table 51. And the spindle motor 1 attached to the support table 52. The spindle motor 1 includes the motor of the above-described embodiment shown in FIG. 1 in a casing 11, and one end of a rotating shaft 10 is exposed from the casing 11. A mounting portion 12 for mounting the processing tool M to one end of the mounting portion 12
And the rotating shaft 10 functions as a spindle. Then, the workpiece W is processed by rotating the processing tool M mounted on the mounting part 12 while moving the work table 51 and the support table 52.

In the machining center of the present embodiment, by providing the spindle motor 1 with the motor of the above-described embodiment, the machining tool M is rotated at a high speed at a stable speed, and is accurately and efficiently received under a good control condition. The workpiece W can be processed.

The present invention is not limited to the above embodiment, and the shape, size, material, etc. of each member can be appropriately changed without departing from the spirit of the present invention. For example, in the above embodiment, the rotary shaft 10 is inserted through the thrust bearing disk 21 and the thrust bearing disk 21 is fixed to the rotary shaft 10.
And the thrust bearing disk 21 may be integrally molded,
Further, the rotary shaft 10 may be divided into two parts, and the thrust bearing disk 21 may be sandwiched and fixed therebetween.

In the above-described embodiment, the thrust bearing portion 20 is provided with a thrust bearing disk 21 made of a magnetic material and an axial electromagnet 22 as thrust bearing means, and the thrust bearing disk 21 is attracted by the axial electromagnet 22. A magnetic bearing is used, but the present invention is not limited to this. As shown in FIG. 4A, a support member 22 'is provided to face the thrust bearing disk 21 in the thrust direction. Dynamic pressure generating means (for generating dynamic pressure between the thrust bearing disk 21 and the support member 22 ′ when the thrust bearing disk 21 rotates, is provided on one of the opposing surfaces of the bearing disk 21 and the support member 22 ′ ( In FIG. 4, the dynamic pressure generating groove 2 is shown.
2′a) may be provided, and the support member 22 ′ may be a dynamic pressure bearing that supports the thrust bearing disk 21 by dynamic pressure generated by the dynamic pressure generating means 22′a during rotation.

The dynamic pressure generating means 22'a is shown in FIG.
As shown in (b), a conventionally known dynamic pressure generating groove 22'a or step is provided on a surface facing one of the thrust bearing disk 21 or the support member 22 ', or a segment is provided. The means can be used without any particular limitation. When the dynamic pressure generating groove is provided, the groove may be a herringbone groove, a spiral groove, or a groove having various shapes.

As shown in FIG. 5, instead of the thrust bearing portion 20 of the above-described embodiment, as shown in FIG. 5, a static pressure generating means (FIG. 5) for generating a fluid pressure between the thrust bearing disc 21 and the support member 22 '. 5, the high pressure gas supply hole 2
2′b) may be provided to form a static pressure bearing or an air bearing in which the thrust bearing disk 21 is supported in the thrust direction by the fluid pressure of the static pressure generating means. The thrust bearing disk 21 is supported by dynamic pressure or fluid pressure, and the rotating shaft 1
When 0 is arranged in the vertical direction, the support member 22 'may be arranged only below the thrust bearing disk 21, and the thrust bearing disk 21 may be floated and supported by dynamic pressure or fluid pressure.

According to the present invention, the rotational speed is not reduced.
It is particularly suitably applied to a motor for high-speed rotation using a non-contact bearing such as a magnetic bearing, a dynamic pressure bearing, a static pressure bearing, or an air bearing as the thrust bearing portion 20 or the radial bearing portion. The bearing is not limited to these non-contact bearings, but may be a slide bearing, a roller bearing, or a ball bearing.

In the above-described embodiment, as the motor unit 30, the rotor unit is provided with the rotor magnet 31, the stator unit is provided with the stator coil 33, and the rotor unit is energized and rotated by the magnetic field formed by the stator coil 31 to rotate. An induction motor or a hysteresis motor including a cage-shaped conductor in the rotor portion and a plurality of pairs of stator coils forming a rotating magnetic field that shifts in the rotation direction of the rotating shaft 10 in the stator portion. You can also.

In the above embodiment, the rotor magnet 3
1 is a cylindrical radial anisotropic multi-pole magnet, but a plurality of 2-pole magnets can be used.

In the above-described embodiment, the rotating body device includes the motor of the embodiment shown in FIG. 1 in the spindle motor 1, but may alternatively include the motor of the above-described modified example. it can. In the above embodiment, the rotating device is a machining center, but the rotating device of the present invention using the motor of the present invention is not limited to this.
The spindle motor may be used alone or in a device other than the machining center. Furthermore, various direct drives such as a hard disk drive and a CD-ROM drive, a polygon mirror motor, various devices including these, and various other devices and devices can be used.

[0028]

As described above, according to the motor of the present invention, stable high-speed rotation can be obtained, and downsizing can be achieved.

According to the rotator device according to the present invention, high-speed rotation can be obtained stably and downsizing can be achieved.

[Brief description of the drawings]

FIG. 1 is an axial sectional view showing a schematic configuration of an embodiment of a motor of the present invention.

FIG. 2 is a cross-sectional view of the motor of FIG. 1 taken along the line AA in FIG. 1;

FIG. 3 is an explanatory diagram showing a schematic configuration of a machining center as one embodiment of a rotating body device of the present invention.

FIG. 4 is a view showing another embodiment of the motor of the present invention, wherein (a) is an axial sectional view showing a schematic configuration,
(B) is a side view of the support member.

FIG. 5 is an axial sectional view showing a schematic configuration of another embodiment of the motor of the present invention.

FIG. 6 is an axial sectional view showing a schematic configuration of a conventional motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spindle motor 10 Rotary shaft 11 Casing 12 Mounting part 20 Thrust bearing part 21 Thrust bearing disk 22 Axial electromagnet 25 Axial sensor 30 Motor part 31 Rotor magnet 32 Protective cover 33 Stator coil 41 Radial bearing sleeve 42 Radial electromagnet 43 Radial direction Sensor 51 Work table 52 Support table

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H605 AA07 AA08 BB05 CC04 CC05 EB02 5H607 AA12 BB01 BB04 BB06 BB14 CC01 DD01 DD02 DD03 FF10 GG01 GG02 GG13 GG17 HH01

Claims (6)

[Claims] A rotating shaft; a projecting portion provided to project radially from the rotating shaft; a projecting portion disposed outside the projecting portion in a thrust direction to face the projecting portion; Thrust bearing means for supporting the overhang in the thrust direction; a rotor disposed at an edge of the overhang; and a rotor disposed radially outward of the rotor to bias the rotor. And a stator member for rotating the protruding portion and the rotating shaft in a direction around the axis thereof. 2. The motor according to claim 1, wherein the overhang portion includes a substantially disc-shaped thrust bearing disk fixed coaxially to the rotation shaft. 3. The overhanging portion includes a magnetic body formed of a magnetic material, and the thrust bearing means sucks or repels the magnetic body in the thrust direction with the magnetic body interposed therebetween. 3. The motor according to claim 1, wherein a magnetic bearing having one or more pairs of coils is used. 4. A dynamic pressure generating means for generating a dynamic pressure when the overhang portion is rotated is provided on one of opposing surfaces of the overhang portion and the support member. The motor according to claim 1 or 2, wherein the protruding portion is supported by the dynamic pressure when the protruding portion rotates. 5. A static pressure generating means for generating a fluid pressure at a portion between the overhanging portion and the support member is provided at one of the overhang portion and the support member. The motor according to claim 1 or 2, wherein the projecting portion is supported in the thrust direction by the fluid pressure. 6. A rotating body device comprising the motor according to any one of claims 1 to 5.