JPS62131736A - Motor spindle - Google Patents

Abstract

PURPOSE:To increase the axial rigidity of a rotor by arranging the rotor driving magnet axially shifted relative to the stator core and energizing the rotor in the shifted direction of the driving magnet by a permanent magnet. CONSTITUTION:A fixed shaft 10 is rotatably supported by a boss 11a of an anchor block 11 and on its outside circumference two dynamic pressure grooves 10a are formed at a predetermined interval. Rotor 20 is composed of a rotating sleeve 21 rotatably fitted into the outside circumference of the shaft 10 and a driving magnet 30 provided on the upper part of the sleeve 21 which are sealed with a housing 50 fixed to the anchor block 11. A stator 60 of the motor is fixed to the housing 50 so as to surround the magnet 30, which is arranged in a little downwardly shifted position from a stator 60. A ring magnet 70 is embedded to the upper end flange 10b of the shaft 10 and a ring magnet 80 to the upper end of the sleeve 21 with polar surfaces facing each other. the permanent magnets 70 and 80 repulse each other and the rotor 20 is energized on the anchor block side to increase the axial rigidity.

Description

DETAILED DESCRIPTION OF THE INVENTION -1 This invention relates to a motor spindle that is improved so that the axial rigidity of the rotor during rotation is increased.

Motor spindles are generally used as drive sources for various devices, but here we will explain the motor spindle used in the rotating mirror optical deflector of Japanese Patent Publication No. 53-6854 with reference to Fig. 3. .

In FIG. 3, the rotating mirror 1a is attached to the upper end of the rotating shaft 1, and the rotary mirror 1a of the motor is mounted at the center of the rotating shaft 1.
is fitted externally. A reinforcing member 3 made of aluminum alloy, titanium alloy, or the like is attached to the lower end of the rotating shaft 1. A rotating magnet 4 of a repulsive magnetic thrust bearing magnetized in the axial direction of the rotating shaft 1 is embedded in this reinforcing material 3. The rotating shaft 1 is supported in the axial direction by the repulsive force between the magnet 5 and the rotating magnet 4. Between the stationary magnet bone 5a and the casing 6, there is a damper 7 made of soft rubber or the like that has a spring action and a vibration suction action.
and rotation in 1 a) are damped by the Dan ri-7. A stator 8 of the motor is attached to the casing 6 so as to face the rotor 2, and the rotating magnetic field generated by the stator 8 causes the rotor 2 to rotate at a target rotation speed.

Vivo-sotos 9 protruding from the casing 6 are arms that support the pads 9a of the hydrodynamic air journal bearing, and three of them protrude on both sides of the motor. Since the pads 9a have the same number of pivots 9, they can freely rotate around the tips of the pivots 9.

Published - Swimming Solution - Leyo Kazuya ↓ - 1 (Separate) Point By the way, in the above-mentioned rotating mirror optical deflector, the weight of the rotating body is supported by the repulsive force of the rotating magnet 4.!: static 1F magnet 5. Because of this, the rigidity in the direction of the rotating rotating body during rotation was not sufficient. This period caused about 6 displacements 17, which caused uneven rotation of the rotating mirror 1a.

The present invention was devised in view of these points, and its purpose is to provide a motor spindle whose rotor has sufficient rigidity in the axial direction during rotation.

1. In order to achieve the above object, the motor spindle according to the present invention has a rotor drive magnet disposed axially offset from the stator core, and The rotor is characterized in that the rotor is urged by a permanent magnet in the direction of displacement of the drive magnet.

If applied to a four-part dish vertical motor, the rotor's own weight will be supported by the axial magnetic force acting between the motor steering wheel and the drive magnet, even if no current is applied, since the drive magnet is a permanent magnet. . After energization, the current value increases as the number of rotations increases, and the magnetic force in the axial direction between the motor stator and the driving magnet increases, so that the driving magnet floats. Also, a permanent magnet? This forces the rotor in the direction of displacement of the drive magnet, so that the rotor is in a balanced state in opposition to the floating blade of the rotor.

Example 141 - [Example 1] Fig. 1 is a vertical cross-section 1 showing an example in which the first embodiment of the present invention is applied to a laser beam scanner II.

In the same figure, reference numeral 10 denotes a fixed shaft supported by the boss Ila of the fixed base 11, and on its outer periphery there are two rings at predetermined intervals, and 5S grooves 10a called lε-n grooves. It is formed.

The rotor 20 is composed of an l-rolling sleeve 21 rotatably fitted around the outer periphery of the fixed shaft 10, and an annular one-acting magneto h30 provided above the rotary sleeve 21. A polygon mirror 40 is attached below the rotating sleeve 21. These are fixed to the fixed base 11)ζ
Although it is sealed with a housing 50, an opening window 51 is opened in the housing 50 so that a part of the polygon mirror 40 can be irradiated with a laser beam from one part. .

A motor stake 60 is fixed to the upper inner surface of the housing 50 so as to surround the driving 7-gun rod 30. Or 7, the driving magnet 3
0 is disposed with a slight downward shift (the amount of shift is indicated by Δ11) with respect to the stator 60 of the motor. Furthermore, a ring-shaped first permanent magnet 70 is embedded in the flange 10b provided at the upper end of the fixed shaft 10 so that one magnetic pole surface thereof is exposed downward, and the rotating sleeve A ring-shaped second permanent magnet 80 is attached to the upper end of the first magnet 21.
The permanent magnet 70 is buried so that the repelling magnetic pole surface faces the exposed magnetic pole surface. In other words, the first permanent magnet 70 and the second permanent magnet 80 repel each other, and the rotor 20 hits the fixed base 11 side and is urged downward. It has become so.

In addition, in the figure, the symbol B is a Hall element f for controlling rotational unevenness of the motor.

Next, the operation will be explained.

The weight of the rotor 20 is supported by the magnetic floating blade of the drive magneto 1-30. As the rotor 20 rotates, pressure in the radial direction is generated by the dynamic pressure grooves 10a, thereby preventing the rotating sleeve 21 from coming into contact with the fixed shaft 10.

At the same time, the first and second permanent magnets 70.80 urge the rotor 20 downward in the axial direction against the force that tends to levitate the rotor 20 upward in the axial direction as the rotor 20 rotates. Therefore, the rotor 20 becomes axially balanced, and the axial rigidity of the rotor 20 increases.

[Embodiment 2] FIG. 2 is a longitudinal cross-sectional view showing an example in which a second embodiment of the present invention is applied to a laser beam printer similar to FIG. 1.

In this second embodiment, the lower end portion or the entire rotating sleeve 21 of the rotor 20 is made of a magnetic material. Further, a ring-shaped permanent magnet 90 is buried in the upper surface of the boss lla of the fixed base 11 so that one magnetic pole surface thereof is exposed.
The exposed magnetic pole surface is opposed to the lower end surface of the rotating sleeve 21 of the rotor 20. In other words, the entire rotor 20 is attracted and biased downward by the permanent magnet 90.

In operation, the weight of the rotor 20 is supported by the magnetic force of the drive magnet 30. On the other hand, the permanent magnet 90 attracts and urges the rotor 20 downward in the axial direction against the force that tends to levitate the rotor 20 upward in the axial direction, so that as a result, the rotor 20 becomes in an axially balanced state. , the axial rigidity of the rotor 20 increases.

Note that, contrary to the second embodiment, the permanent magnet 90 may be disposed at the lower end of the rotor 20 and the fixed base 11 may be made of a magnetic material. Further, although the above description has been made regarding a vertical motor, it goes without saying that the present invention can also be applied to a horizontal motor.

According to this invention, the rotor is supported by the axial magnetic force acting between the stator and the driving magnet, and the permanent magnet counteracts the force that biases the axial magnetic force in the opposite direction. As a result of the force applied to the rotor becoming balanced in the axial direction, the axial rigidity of the rotor increases,
The rotor will rotate stably.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing an example in which the first embodiment of the present invention is applied to a laser beam printer, and FIG.
FIG. 1 is a longitudinal cross-sectional view showing an example in which the embodiment is applied to a laser beam printer similar to FIG. DESCRIPTION OF SYMBOLS 10... Fixed shaft, 11... Fixed base, 20... Rotor, 30... Drive magnet, 60... Stator, 70... First permanent magnet, 80... Second Permanent magnet, 90...Permanent magnet. Patent applicant: NCH N Toyo Bearing Co., Ltd.

Claims (3)

[Claims] (1) A motor spindle characterized in that a driving magnet for the rotor is disposed offset in the axial direction with respect to the core of the stator, and the rotor is biased by a permanent magnet in the direction of the offset of the driving magnet. . (2) A patent characterized in that two permanent magnets are provided at the end of the fixed shaft on which the rotor is rotatably fitted and at the end of the rotor so as to repel each other. A motor spindle according to claim 1. (3) The permanent magnet is provided on a boss of a fixed base that supports the end of the rotor so as to attract and bias the end of the rotor. motor spindle.