JP2567917Y2 - Motors using hydrodynamic bearings - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION The present invention relates to a rotary dynamic pressure generating groove in which a rotating shaft is rotatably inserted into an outer cylinder and at least one of an outer surface of the rotating shaft and an inner surface of the outer cylinder facing each other. And a motor using a dynamic pressure bearing in which an axial dynamic pressure generating groove is formed on at least one of an end of the rotary shaft and a fixed surface facing the end.

2. Description of the Related Art Conventionally, dynamic pressure bearings have been employed as bearings for polygon mirror drive motors for laser printers, VTR cylinder motors, etc. for the purpose of low noise, low vibration or high speed rotation. The conventional back pressure against the dynamic pressure in the axial direction is given by the weight of the rotating portion or a spring provided separately.

[Problems to be Solved by the Invention] However, there is a limit in the back pressure load to be applied by the back pressure by its own weight, so that the degree of freedom is small. Since it has to be arranged, wasteful space is required, which is disadvantageous for motors that are becoming smaller and thinner in the future. In view of the above problems, the present invention provides a back pressure mechanism inside the motor to save space and to enable free design of back pressure.

In the motor using the dynamic pressure bearing of the present invention, a shaft is rotatably inserted into an outer cylinder, and an outer surface of the shaft and an inner surface of the outer cylinder which are opposed to each other. A radial dynamic pressure generating groove is formed on at least one of the shafts, and an axial dynamic pressure generating groove is formed on at least one of one end of the shaft body and a fixed surface facing the end to form a dynamic pressure bearing. Then, an annular rotor magnet is fixed to a hub fixed to the other end of the shaft, and the electric machine is arranged so as to face the rotor magnet from the circumferential direction.
In the motor using a dynamic pressure type bearing fixed child to the fixed part, arranged by shifting the magnetic centers of the magnetic center and the armature of the rotor magnet along the rotational axis,
The component of the magnetic attraction force between the rotor magnet and the armature in the rotation axis direction is used as a back pressure against the dynamic pressure in the axial direction.

According to the above configuration, the rotor magnet provided in the motor as a back pressure for the axial dynamic pressure its
Because it uses magnetic attraction in the direction of the rotation axis with the armature that is circumferentially opposed to the armature , extra permanent magnets and springs are not
In other words, the size and thickness can be reduced .

FIG. 1 is a sectional view of an embodiment of a motor using a dynamic pressure bearing according to the present invention. In FIG. 1, reference numeral 1 denotes a shaft, and a cylindrical hub 2 is fixed to a tip of the shaft. A cylindrical rotor magnet 4 is bonded and fixed to the inside of the hub 2 via a back yoke 3. A disk-shaped thrust plate 6 having a diameter larger than that of the shaft body 1 is fixed to the other end of the shaft body 1 with screws 7. This is the lower surface of the thrust plate 6 dynamic pressure grooves 6a for axial dynamic pressure generated as dynamic pressure is generated on larger concentric circle than the diameter of the shaft 1, as shown in (FIG. 3) is formed, upward Achish
Signal dynamic pressure is generated. Reference numeral 5 denotes an outer cylinder forming a dynamic pressure bearing, which is fixed to a base 9 together with a plate 8 by screws 10 with the shaft 1 inserted from below.
A groove 5a for generating a radial dynamic pressure is formed on the inner periphery of the outer cylinder 5 as shown in FIG.
, The lower surface of the thrust plate 6 and the plate 8
Fluids such as oil are injected between them to form a dynamic pressure bearing. An armature 11 is fixed to the outer periphery of the outer cylinder 5 and faces the inner peripheral surface of the rotor magnet 4.
They are arranged to form a motor with an armature 11 and the rotor magnet 4. The magnetic center 15 of the rotor magnet 4 and the magnetic center 16 of the armature 11 are shifted in the direction of the rotation axis.
Arranged to face the rotor magnet 4 in the circumferential direction
The magnetic attraction between the rotating armatures 11 in the rotation axis direction is
Downward balancing dynamic pressure acting in the upward direction of the spindle
It is used as the back pressure of the vehicle.

As described above, according to the present invention, the back pressure that balances in the opposite direction to the dynamic pressure in the axial direction is used as the magnetic center of the rotor magnet constituting the motor.
Of the armature circumferentially facing the rotor magnet
The air center is shifted along the axis of rotation and
Utilizes magnetic attraction in the direction of the rotation axis of the rotor magnet
It eliminates the need for extra permanent magnets and springs.
You. Furthermore, the radial component that generates the driving force of the motor
Instead, balance the forces of the axial components
Therefore, the rotor magnet and electric
Great freedom in designing the armature and back yoke.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a motor using the dynamic pressure bearing of the present invention.

FIG. 2 is a diagram showing a relationship between a cross section of an outer cylinder used in the embodiment and radial dynamic pressure.

FIG. 3 is a diagram showing a relationship between a thrust plate and an axial dynamic pressure used in the embodiment.

[Explanation of symbols]

 Reference Signs List 1 shaft body 2 hub 3 back yoke 4 rotor magnet 5 outer cylinder 6 thrust plate 7 screw 8 plate 9 base 10 screw 11 armature

Claims (1)

(57) [Scope of request for utility model registration] (1) A shaft body is rotatably inserted into the outer cylinder, a radial dynamic pressure generating groove is formed on at least one of an outer surface of the shaft body and an inner surface of the outer cylinder facing each other, and one end of the shaft body. A groove for axial dynamic pressure generation is formed on at least one of the fixed surfaces opposed to the ends thereof to form a dynamic pressure bearing, and an annular rotor magnet is fixed to a hub fixed to the other end of the shaft body. Armature so as to face the rotor magnet from the circumferential direction.
In a motor using a dynamic pressure bearing in which a rotor is fixed to a fixed portion, a magnetic center of the rotor magnet and a magnetic center of an armature are provided.
Center is shifted along the rotation axis direction,
Of the magnetic attraction between the rotor magnet and the armature
The component is used as the back pressure against the axial dynamic pressure.
A motor using a dynamic pressure bearing.