JP3469601B2 - motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor.

[0002]

2. Description of the Related Art Generally, a motor obtains a rotational force by rotating a rotor magnetized in a predetermined pattern as a rotator attached to a motor shaft by applying a current to a stator side. Here, the motor shaft is rotatably supported by the bearing portion, but some clearance (for example, a few clearances) is provided between the inner peripheral surface of the bearing portion and the outer peripheral surface of the motor shaft in order to realize a good rotation operation. .mu.m to about a few .mu.m is common). Further, it is not possible to completely regulate the position of the motor shaft in the axial direction because it hinders the rotation operation.

Therefore, when the motor shaft rotates, unnecessary movements (shaft movement, vertical movement, pestle movement, etc.) occur in its axial direction (thrust direction) and radial direction (radial direction). For example, in a motor used as a spindle motor of an optical disc player, the influence of such unnecessary movement is represented by vibration of the disc surface, etc., and in some cases, the laser spot irradiated on the disc may maintain an appropriate focus state. In some cases, the data cannot be reproduced because the data cannot be reproduced. Further, the motor for rotating the head drum of the VTR device also affects the recording / reproducing operation. For these reasons, it is desired that the motor used in the precision mechanism part prevent unnecessary movement in the axial direction and the radial direction of the motor shaft.

As a conventionally proposed means for preventing the axial movement of the motor shaft, for example, as shown in FIG. 9, it is held by a bearing portion 33 in a state of abutting against a thrust bearing 32 in a case body 31. In some motors, a restoring force of the leaf spring 40 is used to apply a force to the motor shaft 30 in the direction of the thrust bearing 32 as shown by an arrow F. Reference numeral 34 is an armature winding that serves as a rotator, and 35 is a drive magnet.

As another example, as shown in FIG. 10A, an attraction magnet 42 is provided on the back side of the rotor magnet 37 below the rotary sleeve 36 fixed to the motor shaft 30. The attraction magnet 42 is shown in FIG.
0 (b) is formed in a ring shape as shown as a plan view, and this attraction magnet 42 forms a magnetic path as shown by an arrow F with respect to the inner surface bottom portion of the case body 31 formed of an iron plate, The motor shaft 30 through the rotating sleeve 36
Is pressed against the thrust bearing 32. Reference numeral 38 indicates a stator coil, and 39 indicates an opposing rotor yoke.

On the other hand, as a means for preventing the radial movement of the motor shaft, that is, the movement caused by the clearance C between the motor shaft 30 and the bearing portion 33, as shown in FIGS. A leaf spring 41 is applied to the circumferential surface of the bearing 30 so as to be pressed in the direction of the arrow F to restrict the radial position within the bearing portion 33, or as shown in FIGS.
As described above, by providing the attraction magnet 44 that attracts the rotating plate 43 in the direction of arrow F, the motor shaft 3
It has been proposed to regulate the radial position of the zero bearing portion 33.

[0007]

However, in order to eliminate the unwanted movements in the axial direction and the radial direction at the same time, a preventive mechanism in each direction is required, so that the motor structure becomes complicated. . Further, the contact type using the leaf springs 40, 41 and the like has problems such as changes with time such as wear and mechanical noise and cannot be adopted depending on the device. Although such a problem is solved by the magnetic attraction type, the magnetic attraction type causes a loss in the motor generated driving force due to deterioration of motor cogging (torque ripple) and increase of hysteresis loss at high rotation. There is a drawback that

[0008] By the way, there are also fluid bearings in which the bearing portion is a ball bearing bearing or a fluid such as oil is injected between the motor shaft and the bearing, but these bearings also have similar problems. That is, in the case of the ball bearing bearing, there is a drawback that minute vibration and mechanical noise are generated, and in the case of the fluid bearing, the position of the motor shaft changes between the stationary state and the rotating state of the motor.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a motor capable of eliminating unnecessary axial and radial movements of a motor shaft with a simple structure. For the purpose of providing, a rotorma integrally formed or fixed to a shaft body rotatably supported by a bearing portion.
In a motor having a grnet , the rotor magnet is placed at a predetermined position on the peripheral portion of the inner bottom surface of the motor case body facing the rotor magnet so that a magnetic attraction force is generated in a combined direction of the radial direction and the axial direction of the shaft body. An attraction magnet is arranged so that the magnetic attraction force is not symmetrical in the radial direction, and between the rotor magnet and the attraction magnet in order to prevent the back surface magnetic field from the rotor magnet from leaking to the attraction magnet. A rotor yoke made of a magnetic material is fixed to the rotor magnet.

[0010]

By sucking the rotor in the combined direction of the radial direction and the axial direction, the motor shaft is positioned in a microscopically inclined state by the bearing portion regardless of whether it is stopped or rotated. Will be maintained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the motor of the present invention will be described below with reference to FIGS. FIG. 1 shows the structure of the motor of the embodiment, and this motor 10 is an example used as a spindle motor of an optical disk player. Reference numeral 1 is a turntable, 2 is an optical disk, and 3 is an optical head unit for irradiating laser light onto the optical disk 2 and detecting reflected light thereof to read pit data or magnetic field data recorded on the optical disk 2.

The motor shaft 11 of the motor 10 is mounted on the turntable 1, and the rotation operation of the motor shaft 11 rotationally drives the optical disk 2 mounted on the turntable 1. Reference numeral 12 denotes a pair of bearing portions that rotatably hold the motor shaft 11, and the diameter of the inner peripheral surface of the bearing portion 12 is the motor shaft 1
The diameter is set to be slightly larger than the diameter of 1, and a clearance is provided between the shaft 11 and the shaft 11. Reference numeral 13 is a thrust bearing with which the motor shaft 11 abuts. Bearing part 12
The thrust bearing 13 is fixed in a bearing sleeve 14, and the bearing sleeve 14 is mounted and fixed in a case body 15 which is an outer casing of the motor 10. Reference numeral 16 denotes a stator coil, which is fixed to the case body 15.

Reference numeral 17 denotes a rotary sleeve fixed to the motor shaft 11, and a ring-shaped opposed rotor yoke 18 and a rotor yoke 19 are fixed to the rotary sleeve 17, and the rotor yoke 19 also has an upper surface on which the rotor yoke 19 is fixed. A rotor magnet 20 having a ring shape and having a predetermined magnetization pattern is fixed. Therefore, by applying a current to the stator coil 16 in a predetermined manner, the rotor magnet 20 is rotated and the motor shaft 11 is rotated. The landing pattern of the rotor magnet 20 is as shown in FIG. 4, while the arrangement state of the stator coil 16 is set as shown in FIG.

Here, in this embodiment, the attraction magnet 21 is arranged at a predetermined portion around the inner bottom surface of the case body 15. As shown in the plan view of FIG. 2, the attraction magnet 21 has a ring-shaped 1/4 piece. Further, as shown in FIG. 1 and FIG. 2, it is monopolar magnetized.

By disposing the attracting magnet 21 having such a shape on the periphery of the inner bottom surface of the case body 15,
Rotor yoke 1 made of magnetic material (for example, iron)
For 9, there is a magnetic path such that the motor shaft 11 is attracted in the axial direction as shown by arrow F _{1 in} FIG. 1 and the motor shaft 11 is attracted in the radial direction as shown by arrow F _{2 in} FIG. It is formed. That is, the motor shaft 1 is moved by the attraction magnet 21.
1 is attracted in the combined direction of the radial direction and the axial direction, in other words, an inclination force toward the magnetic force center direction of the attraction magnet 21 is applied to the motor shaft 11.

For this reason, the motor shaft 11 is extremely illustrated in FIG.
Positioning is performed with an inclination θ with respect to the vertical direction viewed from 2, and the state is maintained not only during stop and during rotation. Therefore, unnecessary radial movement of the motor shaft 11 is eliminated. The inclination angle θ is on the order of minutes (less than 1 °) in the normal clearance setting. Further, when viewed in the axial direction, the motor shaft 11 has a suction force acting in a direction in which the motor shaft 11 is pressed against the thrust bearing 13, so that unnecessary movement in the axial direction is eliminated.

Further, in this embodiment, the attraction magnet 2
No. 1 is monopolar magnetization, and the attraction force is not affected by the rotation angle of the rotating body. That is, the attraction force to the rotor yoke 19 does not change during rotation. Therefore, the cogging (torque ripple) is not deteriorated by mounting the attraction magnet 21 and does not cause a hysteresis loss. For this reason, the plate thickness of the rotor yoke 19 is selected so that the back magnetic field of the rotor magnet 20 does not leak. Of course, since it is not a contact type, there is no problem of aging or mechanical noise.

FIG. 6 shows a second embodiment in a simple manner. FIG. 6 (a) is an arrangement relationship diagram of the motor shaft 11 and the attraction magnet 21 as seen from the plane direction, and FIG. 6 (b) is a motor shaft 1
1 shows the positional relationship between the attraction magnet 21, and the rotor 22 (magnetic material) fixed to the motor shaft 11 in a sectional view from the side. Note that the rotor 22 is the same as that shown in FIG.
As for the motor configuration of the embodiment of FIG.
7, the opposing rotor yoke 18, the rotor yoke 19, and the rotor magnet 20 correspond.

As can be seen from the drawing, the attraction magnet 21 has a circular planar shape and is arranged below the rotor 22. Even in this case, as in the first embodiment, the attraction magnet 21 exerts an attraction action on the motor shaft 11 in the combined direction F _{M of the} F ₁ direction and the F ₂ direction, and the same effect can be obtained. You can

Further, FIGS. 7A and 7B show a third embodiment. In this case, the attraction magnet 21 is in the shape of a ring having an outer circle and an inner circle whose center points are deviated. Even with this shape, since the attraction magnetic path is formed in the synthetic direction F _M , the same effect can be obtained.

The shape and arrangement position of the attraction magnet 21 can be further considered, and in any case, the attraction can be applied to the motor shaft 11 in the combined radial and axial directions. Good.

FIG. 8 shows a fourth embodiment of the present invention applied to a general DC brush motor. Reference numeral 23 is an armature winding, 24 is a drive magnet, and 25 is a rotating plate made of a magnetic material. The armature winding 23 and the rotating plate 25 are fixed to the motor shaft 11. Also in this case, the attraction magnet 21 is arranged in a part of the peripheral portion of the inner bottom surface of the case body 15 in a shape as shown in FIG. 8B, and the rotating plate 25 is combined with the radial direction of the motor shaft 11 and the axial direction. The same effect as in each of the above-described embodiments can be obtained by suctioning.

Various other examples of the present invention are conceivable, and the shape and arrangement position of the attraction magnet should be changed according to the structure and shape of the motor.

[0024]

As described above, the motor of the present invention is
With a very simple structure of providing a magnet means for forming a magnetic path for attracting the rotor integrally molded or fixed to the shaft body in the combined direction of the shaft body radial direction and the axial direction, There is an excellent effect that unnecessary movements such as vibration and shake in the axial direction can be eliminated, and, of course, the position of the motor shaft does not change during rotation and stop. Therefore, it is very suitable as a motor for driving precision equipment or precision parts.

[Brief description of drawings]

FIG. 1 is a structural diagram of a first embodiment of a motor of the present invention.

FIG. 2 is a plan view of the attraction magnet according to the first embodiment.

FIG. 3 is an explanatory diagram of a motor shaft attraction state by the attraction magnet of the first embodiment.

FIG. 4 is an explanatory diagram of a magnetization pattern of the rotor magnet according to the first embodiment.

FIG. 5 is an explanatory diagram of an arrangement state of stator coils according to the first embodiment.

FIG. 6 is an explanatory diagram of a second embodiment of the motor of the present invention.

FIG. 7 is an explanatory diagram of a third embodiment of the motor of the present invention.

FIG. 8 is an explanatory diagram of a fourth embodiment of the motor of the present invention.

FIG. 9 is an explanatory diagram of a conventional axial position regulation system for a motor shaft.

FIG. 10 is an explanatory diagram of a conventional axial position regulation system for a motor shaft.

FIG. 11 is an explanatory diagram of a conventional radial position regulation system for a motor shaft.

FIG. 12 is an explanatory diagram of a conventional radial position regulation system for a motor shaft.

[Explanation of symbols]

10 motors 11 motor shaft 12 Bearing 13 Thrust bearing 14 Bearing sleeve 15 case body 16 stator coil 17 rotating sleeve 18 Opposing rotor yoke 19 rotor yoke 20 rotor magnet 21 suction magnet 22 rotor 23 Armature winding 24 drive magnet 25 rotating plate

Continuation of the front page (56) References JP-A-62-272841 (JP, A) JP-A-62-77032 (JP, A) JP-A-2-216664 (JP, A) Actual Kaihei 4-58065 (JP , U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K ⁷ /00-7/20 H02K 5/00-5/26 G11B 19/20-19/28

Claims (4)

(57) [Claims] 1. A motor having a rotor magnet integrally molded or fixed to a shaft body rotatably supported by a bearing portion, wherein the rotor magnet is magnetically attracted in a combined direction of the radial direction and the axial direction of the shaft body. So that the magnetic attraction force is not symmetrical in the radial direction at a predetermined position in the peripheral portion of the inner bottom surface of the motor case body facing the rotor magnet, A motor in which a rotor yoke formed of a magnetic material is disposed between the rotor magnet and the attraction magnet in a fixed manner to the rotor magnet in order to block leakage of a back surface magnetic field to the attraction magnet. . 2. The motor according to claim 1, wherein the shape of the attraction magnet is a ring-shaped quarter piece. 3. The motor according to claim 1, wherein the shape of the attraction magnet is a ring shape composed of an outer circle and a inner circle whose center points are displaced. 4. The motor according to claim 1, wherein the magnetizing pattern of the attraction magnet is a single pole magnetized.