JPH0765612B2 - Dynamic pressure gas bearing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dynamic pressure used in a rotary unit having a built-in motor such as a rotary cylinder for a VTR (video tape recorder), a rotary drive motor for a magnetic disk device, a rotary polygon mirror, and the like. The present invention relates to a gas bearing device.

2. Description of the Related Art In recent years, in VTRs, magnetic disk devices, etc., it has become necessary to reduce the precision and torque of the bearings at the heart of the VTRs, dynamic pressure type fluid bearings, and among them gas bearings with low bearing friction torque. The need for is increasing.

Hereinafter, an example of the above-described conventional gas bearing device will be described with reference to the drawings. FIG. 5 shows a conventional gas bearing device. In FIG. 5, reference numeral 1 is a chassis, and a housing 2 is fixed to the chassis 1. A shaft 4 having a hub 4B is rotatably inserted into the housing 2. Shaft 4 has disc flange 4A and end 4C
have. A bottom plate 3 is attached to the housing 2, and a dynamic pressure generating groove 3A is provided on a contact surface with the end portion 4C.
Generates pressure between 4C and levitates and rotates without contact. Axis 4
There is a herringbone-shaped dynamic pressure generating groove 5A, 5B on either the outer circumference or the inner circumference of the housing 2 for non-contact rotation. A motor rotor 6 is attached to the shaft 4 having a hub 4B in the upper portion, and a motor stator 7 is attached to face the inside of the housing. A disk 8 and a spacer 9 are inserted into the hub 4B and fixed by a disk fixing plate 10.

Regarding the dynamic pressure gas bearing device configured as described above,
The operation will be described below. First, when the motor stator 6 is energized, the motor rotor 6 rotates together with the shaft 4, the disk 8, the spacer 9, and the disk fixing plate 10, and floats and rotates by the dynamic pressure generating grooves 5A and 3A.

SUMMARY OF THE INVENTION However, the above-mentioned configuration has the following problems. That is, the static electricity generated during rotation discharges on the surface of the radial gas bearing, which prevents stable rotation for a long time, which adversely affects the life of the gas bearing.

Means for Solving the Problems In order to solve the above problems, a gas bearing device of the present invention comprises a stepped fixed shaft that is erected on a chassis and has a large diameter part and a small diameter part, and a large size of this fixed shaft. A sleeve rotatably attached to a diameter portion, a stopper fixed to a free end portion of the fixed shaft and engaged with a step portion of the sleeve, a rotating disc attached to an end portion of the sleeve, A thrust bearing provided between a disc and either one of the shaft end face or the stopper end face, holds a conductive lubricant in the thrust bearing, and has a herringbone type on either the shaft or the sleeve. Alternatively, a helical dynamic pressure generating groove is provided, and a motor is arranged between the chassis and the large diameter portion of the fixed shaft and around the small diameter portion.

Action The present invention is to obtain a dynamic pressure gas bearing device having a long life without discharge at the bearing portion by the above-mentioned configuration.

Example Hereinafter, a dynamic pressure gas bearing device of one example of the present invention,
A description will be given with reference to FIGS. 1 to 4. FIG. 1 is a sectional view of a dynamic pressure gas bearing device of the present invention. In FIG. 1, 11 is a chassis, 12 is a fixed shaft having a large diameter portion 12A and a small diameter portion 12B, and is fixed to the chassis 11 with screws or the like. Reference numeral 13 denotes a sleeve, which is rotatably inserted into the outer periphery of the shaft 12 and has a flange portion 13c and a step portion 13d. A stopper 14 is fixed to the upper part of the solid shaft 12 by screws or the like,
The stopper 14 enters the step portion 13d of the sleeve 13 and prevents the rotating body from coming off. A thrust bearing 15 having a spiral groove 15A is swingably provided by a protrusion 14A at the center of the stopper 14. The thrust bearing 15 is prevented from rotating by a turning pin 17. The dynamic pressure generating groove 15A functions as a thrust bearing, but holds a conductive lubricant 18 such as conductive oil or conductive grease. Inner circumference of sleeve 13 or large diameter part of fixed shaft 12
On the outer circumference of 12A, the length B1 on the upper side in the figure shown in FIG. 2 is longer than the lower B2 herringbone groove 13A, or as shown in FIG. It has a helical groove 13B for carrying it down. The rotating disk 16 has an intake hole 16A through which gas passes and a filter 21 for guiding clean gas, and a disk 23 and a spacer 22 are fixed by the rotating disk 16. A motor rotor 19 is fixed to the sleeve 13 by means such as caulking. 20 is a motor stator, which is the large diameter portion 12A of the fixed shaft 12 and the chassis 11
Power is supplied from the lead wire of 20A, which is fixed between the small diameter portion 12B and the small diameter portion 12B. As the conductive lubricant 18, ester oil or olefin oil is used as a main raw material, and carbon, graphite, metal powder or the like is added.

Regarding the dynamic pressure gas bearing device configured as described above,
The operation will be described with reference to FIGS. In FIG. 1, when the motor stator 20 is energized, the motor rotor 19 starts to rotate together with the sleeve 13, the disk 23, the spacer 22, the rotating disk 16, and the thrust bearing 15. Since the motors 19 and 20 are located around the small diameter portion 12B of the fixed shaft 12, the motors can be made compact. At this time, the dynamic pressure generating groove 13A or 13B for the radial bearing generates pressure in the gas and rotates without contact. Further, the dynamic pressure generating groove 15A for the thrust bearing also applies pumping pressure to the conductive lubricant 18 such as oil or grease to rotate without contact. By using the conductive lubricant 18 in the dynamic pressure generation groove 15A,
Static electricity generated in the rotating body can be released to the fixed body, and the bearing device can be stably and continuously rotated. The dynamic pressure generating grooves 13A and 13B for the radial bearings serve to convey the gas from the top to the bottom while increasing the pressure in FIG. 1 during rotation, and the gas is cleaned by the filter 21. Since it is supplied from the intake hole 16A, dust does not enter the bearing gap and the gas bearing is not burned.

As described above, according to the present embodiment, static electricity generated during rotation is grounded to the fixed body, discharge at the bearing part is prevented, and gas is also cleaned by the filter and supplied, so stable for a long period of time. Then you will be able to rotate.

It should be noted that the thrust bearing may not be the dynamic pressure type bearing shown in FIG. 4, but a conductive lubricant may be used for a pivot bearing (not shown), for example.

EFFECTS OF THE INVENTION As described above, the present invention provides a dynamic pressure gas bearing device that can be continuously and stably rotated for a long time by using a dynamic pressure type gas bearing as the radial bearing and using conductive lubrication for the thrust bearing. In addition, since the motor is arranged around the small diameter portion of the fixed shaft, the motor can be made compact.

[Brief description of drawings]

FIG. 1 is a sectional view of a gas bearing device according to an embodiment of the present invention,
The second is a pattern diagram of the dynamic pressure generating groove of the radial gas bearing, FIG. 3 is a diagram of a modified application example of the dynamic pressure generating groove pattern, FIG. 4 is a detailed view of the thrust bearing of the same embodiment, and FIG. It is sectional drawing of the conventional gas bearing apparatus. 11 …… Chassis, 12 …… Fixed shaft, 13 …… Sleeve, 13
A, 13B …… dynamic pressure generating groove, 13D …… step, 14 …… stopper, 15 …… thrust bearing, 16 …… rotating disc, 16A ……
Intake hole, 18 ... Conductive lubricant, 21 ... Filter.

Claims (1)

[Claims] 1. A stepped fixed shaft that is erected on a chassis and has a large diameter portion and a small diameter portion, a sleeve rotatably attached to the large diameter portion of the fixed shaft, and a free end of the fixed shaft. A stopper that is fixed to the portion and that engages with the stepped portion of the sleeve, and a rotating disk attached to the end portion of the sleeve,
A thrust bearing provided between the rotating disc and either one of the shaft end surface or the stopper end surface, holds a conductive lubricant in the thrust bearing, and herrings either one of the shaft and the sleeve. A dynamic pressure gas bearing device in which a bone type or helical type dynamic pressure generating groove is provided, and a motor is arranged between the chassis and the large diameter portion of the fixed shaft and around the small diameter portion.