JP2003224942A - Electromagnetic rotating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic rotating machine capable of providing high-speed rotation. <P>SOLUTION: This machine comprises a rotor magnet which is fixedly jointed to a rotating shaft or a rotating sleeve through a flange which is integrally rotated with the rotating shaft or the rotating sleeve, a bearing member which supports the rotating shaft or the rotating sleeve so as to be freely rotatable, a base fixedly jointed to the bearing part, first fixed yokes, second fixed yokes facing the first fixed yokes, and a coil member which is wound around the first or the second fixed yokes. The plurality of the first fixed yokes and the second fixed yokes, facing each other and having an air gap in the rotational direction, are arranged coaxially around the bearing member, and the rotator magnet is disposed in the air gap. A cylindrical reinforcement member which has a plurality of opening parts is stuck at an outer edge part of the rotor magnet in the radial direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic rotating machine, and more particularly to a polygon mirror scanner motor (hereinafter referred to as a scanner motor) used in a laser beam printer (hereinafter referred to as LBP) and a spindle motor for a DVD drive device. Is.

[0002]

2. Description of the Related Art In recent years, LBP is required to have high speed and high accuracy, while SOHO (Small Office a
Demand for smaller size and lower price is also increasing for nd home office). The scanner motor, which is a major component of the laser scanner unit, is also required to be miniaturized. For this purpose, it is necessary to achieve miniaturization without reducing the generated torque and to achieve the contradictory characteristics of low vibration. . To achieve these requirements,
A spindle motor (PAM: Para-Axial-Motor) having a shape in which a stator yoke extends in the axial direction.
Is proposed. For example, Japanese Patent Laid-Open No. 2001-7
The electromagnetic rotating machine described in 8416 is a suitable example.

FIG. 5 and FIG. 6 are examples of the structure of the PAM described in the above patent publication. Fig. 5 shows the PA seen from above the rotation axis.
FIG. 3 is a plan view showing a part of M in a cross section, and the right half is a view in which a rotor including a rotor magnet 60, a flange 70, a rotating shaft 80, and a polygon mirror 100 is removed.
FIG. 6 is a cross-sectional view as seen from a direction perpendicular to the rotation axis. The left half is a cross-sectional view taken along a plane including the rotation axis, and the right half is a cross-sectional view showing the outer yoke retainer 50 removed.

The difference from the conventional axial gap motor is the configuration of the magnetic circuit, which is extended in the axial direction instead of the fixed yoke of the laminated stator core extending in the radial direction and the winding coil wound around the fixed yoke. The fixed yoke 10 and the drive coil 20 are used. As shown,
The pair of inner yoke 11 and outer yoke 12 extends in the direction of the rotation axis to form an air gap. A cylindrical rotor magnet 60 is arranged in the air gap as shown in the drawing, and a magnetic gap pair 17 (air gap pair) is formed by forming two pairs on the inner circumference side and the outer circumference side of the rotor magnet 60. Thus, a plurality of magnetic gap pairs are arranged around the rotation axis.

With reference to FIG. 5 and FIG.
The basic configuration of PAM described in 01-78416 will be described. The fixed yoke 10 includes an inner yoke 11 that is a first fixed yoke that is a cylindrical portion having a rotation axis as a symmetrical axis, a ring-shaped bottom plate portion 13 that is perpendicular to the rotation axis, and a rotation axis that is parallel to the cylindrical surface of the inner yoke 11. The outer yoke 12 is a second fixed yoke having a plurality of independent facing surfaces extending in the direction. The number of independent facing surfaces is 6 in the figure. That is, the number of drive coils 20 is also 6, and the outer yoke 1
It has been wound into 2. The fixed yoke 10 is made by drawing or M
Integral processing is possible by IM (Metalin Mold) or the like.

The fixed yoke 10 is fixed to the bearing sleeve 40 together with the circuit board 30 (or base). The fixed yoke 10 is guided and inserted into the outer shape of the bearing sleeve cylindrical portion 43, and then adhered to the bearing sleeve disk portion 41. The circuit board 30 has a bearing sleeve disk portion outer peripheral portion 42.
The bearing sleeve 40 is caulked and fixed by a plurality of caulking portions (not shown) formed on the.

Reference numeral 50 denotes a resin-made outer yoke holder. A groove (not shown) corresponding to the shape of the outer yoke 12 is formed on the inner peripheral side of the outer yoke retainer 50, and the outer yoke 12 is inserted and fitted and fixed by pressing. Since the drive coil 20 is also inserted into the outer yoke 12, the outer yoke retainer 50 simultaneously presses and fixes the drive coil 20 as well. Outer yoke 12 of outer yoke retainer 50
The fixing method is performed by press-fitting and then bonding. The outer yoke retainer 50 serves as an exterior of the illustrated electromagnetic rotating machine and suppresses vibration of the outer yoke 12 due to electromagnetic interaction with the rotor magnet 60.

The six drive coils 20 are sequentially energized as U-, V-, and W-phase armatures, respectively. The rotational position of the rotating magnetic field of the rotor magnet 60 is detected by detecting an electromotive force from an electric element that is not energized,
A current drive circuit (not shown) for the armature switches the drive current of the coil of each phase at an appropriate timing. Thus, the rotating body including the rotor magnet 60 rotates smoothly.

Next, the structure of the rotating body will be described. As shown in FIG. 7, the rotor magnet 60 of the flange 70 that is press-fitted or shrink-fitted onto the rotary shaft 80 is molded.
A plurality of rotor magnets 60 outsert-molded on the flange 70 are alternately magnetized in the radial direction. In FIG. 5, since the number of poles of the drive coil 20 and the outer yoke 12 is 6, the number of magnetic poles attached to the rotor magnet 60 is 8. The rotor magnet 60 has a magnetic gap shown in FIG.
That is, when the drive coil 20 is arranged in a space formed by the inner yoke 11 and the outer yoke 12 and a suitable drive coil 20 is energized, torque is generated on both inner and outer peripheral surfaces of the rotor magnet 60. Here is the PA compared to the radial gap motor
This is the reason why the torque generated by M becomes large. That is, in the radial gap motor, the torque generation place is one place on one side inside or outside the rotor magnet.
In the motors shown in FIGS. 5 and 6, there are two torque generation points on the inner circumference side and the outer circumference side of the rotor magnet 60.

The rotary shaft 80 is rotatably supported by a thrust bearing 90 in the thrust direction and a fluid bearing (inner diameter portion of the bearing sleeve 40) in the radial direction. After the motor is completed, the polygon mirror 100 is fixed on the flange 70 as shown in FIG.

The drive coil 20 can be wound on a bobbin 21 formed of an insulating resin by using a uniaxial winding machine. The wire 22 is wound around a bobbin after the start end is wound around the terminal pin 23, and the end is twisted around the remaining terminal pin 23 to complete the drive coil 20. The drive coil 20 is inserted in the outer yoke 12 as shown in the drawing. Terminal pin 23
Is soldered to the circuit pattern formed on the circuit board 30 (base) and a drive current is supplied from the drive circuit. Appropriate drive current control is performed for each coil as U phase, V phase, and W phase.

As shown in the sectional view on the left side of FIG. 5, the magnetic gap formed by the inner yoke 11 and the outer yoke 12 of the fixed yoke 10 is occupied by the rotor magnet 60 and the drive coil 20, so that one layer of the drive coil 20 is formed. By adjusting the number of windings and the effective length of the magnetic gap portion of the rotor magnet 60, it becomes possible to design a motor having various starting torque-driving current relationships. In addition, compared to radial gap motors, the winding space can be taken wider, so
The number of windings can be increased and power saving design is possible.

To summarize the above, Japanese Patent Laid-Open Publication No. 2001-2001
Since the PAM shown in -78416 has a shape in which the stator yoke extends in the axial direction, the space around the bearing can be effectively used, and in particular, the motor can be downsized in the radial direction. Since the rotor magnet and the drive coil are arranged in the axially narrow gap formed by the inner yoke and the outer yoke, as described above, even if the size is reduced, a certain winding space can be secured, so that the drive current is kept constant. The required generated torque can be obtained without increasing.

Further, since the coil wound around the bobbin is arranged on the fixed yoke, the coil can be assembled by a uniaxial inexpensive winding machine. Further, since the coil can be easily arranged on the fixed yoke, the number of assembling steps can be reduced. Further, since the fixed yoke can be manufactured by forging or pressing, it is possible to significantly reduce the cost.

[0015]

In the above-mentioned conventional example,
With a configuration (para-axial-motor: PAM) in which the winding coil axis, the rotor magnet rotation axis, and the stator core extension direction and the axis of symmetry are arranged in parallel, it is possible to reduce the diameter of the motor and increase the torque.

However, in recent years, the scanner motor has been increased in rotation speed, and a rotation speed of 30,000 rpm or more is required. At such a rotation speed, the rotor magnet shown in FIGS. 5 and 6 of the conventional example may be damaged by the internal stress generated by the centrifugal force. Further, as a general configuration, there is a structure in which a rotor magnet is fixed or outsert-molded to the inner wall of the outer edge of the pressed rotor yoke to increase the breaking strength at high speed rotation. However, when this configuration is applied to the conventional example shown in FIGS. 5 to 7, the magnetic gap on the outer peripheral side of the magnetic gap pair 17 shown in FIG. 6 does not contribute to torque generation.

Therefore, an object of the present invention is to provide an electromagnetic rotating machine that can rotate at high speed.

[0018]

In order to achieve the above object, in the present invention, a cylindrical reinforcing member having a plurality of openings in the radial direction is fixed to the outer edge portion of a rotor magnet shown in the conventional example. , Prevents damage to the magnet during high-speed rotation. Further, the number of openings is equal to or greater than the number of magnetized magnetic poles of the rotor magnet, and each magnetized center of the rotor magnet is substantially coincident with the center of the corresponding opening of the reinforcing member, The rotor magnet is configured to be filled in the opening. With this, an appropriate magnetic gap can be formed between the outer yoke and the rotor magnet, so that torque is generated.

Further, with respect to the magnetic gap pair 17 shown in FIG. 6, the magnetic gap width on the inner peripheral side and the magnetic gap width on the outer peripheral side are adjusted so that the combined force received by the drive magnets other than the circumferential component. The force of is canceled and the vibration caused by the force in the radial direction can be suppressed.

A PAM (Para-Axici) having the above configuration
In the al-motor), the internal stress of the rotor magnet generated by the centrifugal force during high speed rotation is dispersed by the reinforcing member.

Further, since the opening of the reinforcing member is filled with the rotor magnet member and the opening is used as the magnetizing center, the positive magnetic interaction between the outer yoke and the rotor magnet is guaranteed, so that the generated torque is reduced. It is possible to provide a PAM that can rotate at high speed without dropping.

Further, by setting the magnetic gap width on the inner circumference side and the magnetic gap width on the outer circumference side to optimum values, unnecessary vibration can be suppressed and the rotation accuracy can be improved.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the configuration of an electromagnetic rotary machine that is Embodiment 1 of the present invention. A description of the same parts and configurations as those of the conventional example will be omitted. FIG. 1 is a partial cross-sectional view as seen from a direction perpendicular to the rotation axis. The left half is a cross-sectional view taken along a plane including the rotation axis, and the right half is a plan view showing the outer yoke retainer 50 removed. is there.

The difference from the conventional example is the method of constructing the rotating body including the rotor magnet 61. In the present invention, instead of the drive magnet 60 being outsert-molded on the flange 70 (see FIG. 6), the rotor magnet 6
The rotor yoke 14 in which 1 is fixed or outsert-molded is fixed to the flange 70 by caulking. The rotor yoke 14 is drawn from a sheet metal, and has an effect of receiving and dispersing an internal stress generated in the rotor magnet 61 by a centrifugal force during high speed rotation. Therefore,
The rotor magnet 61 reinforced by the rotor yoke 14 does not break even at a high rotational speed of 30,000 rpm or more.

FIG. 2 is a plan view (upper diagram) and a cross-sectional view (lower diagram) showing the structure of the rotating body which is a feature of the present invention. As is clear from the figure below, the rotor yoke 14 has a plurality of openings 15, and the openings 15 are filled with a rotor magnet 61. The rotor magnet 61 is fixed to the rotor yoke 14 or is outsert-molded. The upper diagram of FIG. 2 is a cross-sectional view (cross-section AA in the lower diagram of FIG. 2) for explaining the opening 15 and the magnetized position. In this embodiment, the magnetizing direction of the rotor magnet 61 is the radial direction and the number of poles is eight. The number of openings 15 is also eight, which is the same as the number of poles. Further, it is characterized in that the magnetization center and the center of the opening are substantially coincident with each other. When the outer yoke is excited, the rotor magnet 6 filled in the opening 15
When 1 is the magnetization center, the magnetic interaction with the outer yoke 12 is not suppressed, and the generated torque is not impaired even when compared with the conventional example.

FIG. 3 shows a rotating body including a rotor yoke which is Embodiment 2 of the present invention. The difference from Example 1 is that
This means that the size of the openings 16 in the circumferential direction is reduced, and instead, the number of the openings 16 is quadrupled to 16. When the opening 15 in the first embodiment is too large to sufficiently disperse the internal stress near the center of the opening of the rotor magnet 61, it is effective to make the opening small. Also in the second embodiment, the magnetization center substantially coincides with the opening 16.

FIG. 4 is a partial sectional view of the fixed yoke portion for explaining the method of setting the air gap (magnetic gap).
In this embodiment, the inner yoke has a cylindrical shape and the outer yoke has a plurality of salient poles. Each air gap width, the inner circumference side air gap width 171, and the outer circumference side air gap width 172 are determined so as to satisfy the following conditions. Radial force received by rotor magnet = Radial attraction force of outer yoke + Radial attraction force of inner yoke ≈ 0 By canceling the combined force in the radial direction, unnecessary vibration is eliminated and rotation accuracy is improved.

[0028]

As described above, in the PAM (Para-Axial-Motor) to which the present invention is applied, the internal stress of the rotor magnet generated by the centrifugal force during high speed rotation is dispersed by the reinforcing member.
Further, since the opening of the reinforcing member is filled with the rotor magnet member and the opening is used as the magnetization center, the positive magnetic interaction between the outer yoke and the rotor magnet is guaranteed, so that the generated torque is not reduced. A PAM that can rotate at high speed can be provided. Therefore, it is most suitable for a polygon scanner motor that requires high speed rotation of 30,000 rpm or more.

Further, in the PAM type spindle motor, the magnetic gap width (air gap width) on both sides of the drive magnet can be adjusted to cancel the generated force other than in the circumferential direction, thereby eliminating unnecessary vibration and improving the rotation accuracy. To do. In the polygon mirror scanner motor, the standard for the mass balance of the rotating body can be expanded.

[Brief description of drawings]

FIG. 1 is a sectional view of an electromagnetic rotating machine that is Embodiment 1 of the present invention.

FIG. 2 is a sectional view of a rotating body that is Embodiment 1 of the present invention.

FIG. 3 is a sectional view of a rotating body that is Embodiment 2 of the present invention.

FIG. 4 is a cross-sectional view illustrating a method of designing a magnetic circuit according to the present invention.

FIG. 5 is a cross-sectional view illustrating a conventional PAM type polygon mirror scanner motor.

FIG. 6 is a cross-sectional view illustrating a conventional PAM type polygon mirror scanner motor.

FIG. 7 is a sectional view of a rotating body of a conventional PAM type polygon mirror scanner motor.

[Explanation of symbols]

10 fixed yoke 11 Inner yoke 12 Outer yoke 14 rotor yoke 15, 16 openings 17 Magnetic Gap Pair (Air Gap Pair) 20 drive coil 30 circuit board (base) 40 Bearing sleeve 50 Outer yoke holder 60, 61 rotor magnet 70 flange 80 rotation axis 90 thrust bearing 100 polygon mirror

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02K 21/12 H02K 21/12 MF term (reference) 5H002 AA08 AA09 AB05 AB06 AB07 AC07 AE02 AE08 5H621 GA02 GA07 GA12 GA16 GA17 GB03 GB10 HH01 HH08 JK05 5H622 CA01 CA05 CB04 PP05 PP10 PP17 PP20

Claims (3)

[Claims] 1. A rotor magnet coupled and fixed to a rotary shaft or a rotary sleeve via a flange and rotating integrally with the rotary shaft or the rotary sleeve, and a bearing for rotatably supporting the rotary shaft or the rotary sleeve. A member, a base fixedly coupled to the bearing portion, a first fixed yoke, a second fixed yoke facing the first fixed yoke, and a coil wound around the first or second fixed yoke. A plurality of members, the first fixed yoke and the second fixed yoke, which face each other and have an air gap in the rotation axis direction, are arranged concentrically around the bearing member, and the rotor magnet has the air gap. In the electromagnetic rotating machine configured to be disposed inside, a cylindrical reinforcing member having a plurality of openings in the radial direction is fixed to the outer edge of the rotor magnet. Electromagnetic rotating machine, characterized in that there. 2. The number of the openings is equal to or greater than the number of magnetized magnetic poles of the rotor magnet, and the magnetization center of each of the rotor magnets is the same as that of the corresponding opening of the reinforcing member. The electromagnetic rotating machine according to claim 1, wherein the rotor magnet is substantially coincident with a center and the rotor magnet is filled in an opening of the reinforcing member. 3. A rotor magnet coupled and fixed to a rotary shaft or a rotary sleeve via a flange and rotating integrally with the rotary shaft or the rotary sleeve, and a bearing for rotatably supporting the rotary shaft or the rotary sleeve. A member, a base fixedly coupled to the bearing portion, a first fixed yoke, a second fixed yoke facing the first fixed yoke, and a coil wound around the first or second fixed yoke. A plurality of members, the first fixed yoke and the second fixed yoke, which face each other and have an air gap in the rotation axis direction, are arranged concentrically around the bearing member, and the rotor magnet has the air gap. In the electromagnetic rotating machine configured to be disposed inside, the width of the first air gap formed by the first fixed yoke and the drive magnet and the second fixed yaw. The width of the second air gap formed by the drive magnet and the drive magnet is set so that the forces other than the circumferential component of the combined force received by the drive magnet are substantially canceled. Rotating machine.