Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
1998-09-28
2001-01-16
Nguyen, Hoa T. (Department: 2754)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
C137S047000, C310S090000, C384S100000, C384S107000
Reexamination Certificate
active
06175547
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a positive and negative rotation gas dynamic pressure bearing, a spindle motor, and a rotator device which are able to open and close a conducting hole to generate a lubricating function of a pump-out effect without an electromagnetic switching valve, and which are able to decrease run out because dynamic pressures generating at dynamic pressure generating grooves arranged equally toward a circumference direction during rotation and generating a lubricating function of a pump-in effect to close the conducting hole are all equal.
A positive and negative rotation gas dynamic pressure bearing is a gas dynamic pressure bearing which generates a lubricating function of a pump-in effect to increase dynamic pressure at central portions of the dynamic pressure generating grooves taking in lubricating gas from both ends of the dynamic pressure generating grooves during rotation in one of positive and negative rotations, and which generates a lubrication function of a pump-out effect to increase dynamic pressure at both ends of the dynamic pressure generating grooves and to receive a supply of lubricating gas from the central portions middle of the dynamic pressure generating grooves during rotation in the other of the positive and negative rotations.
As conventional positive and negative rotation gas dynamic pressure bearings, two articles are disclosed: “Positive and negative rotation herringbone journal gas bearing using both of pump-in type and pump-out type”, Vol. 58, No. 555 in collection published by Mechanical Society of Japan (article No. 92-0550, Article 1, hereafter), and “Positive and negative rotation gas lubrication disc thrust dynamic pressure group bearing”, Vol. 59, No. 568 in collection published by Mechanical Society of Japan (article No. 93-0465, Article 2, hereafter.)
In Article 1, a plurality of herringbone dynamic pressure generating grooves which are substantially V-shaped and shallow are formed with equal arrangement toward a circumference direction at an outer circumference surface of a shaft constituting a rotation bearing member. Three conducting holes are bored at a sleeve constituting a bearing stationary member supporting the shaft and are disposed at center portions of herringbone dynamic pressure generating grooves at intervals of 120 degrees, and the conducting holes become supplying paths of the air outside when the three conducting holes generate a lubricating function of a pump-out effect.
In Article 2, herringbone dynamic pressure generating grooves which are substantially L-shaped are formed with equal arrangement toward a circumference direction at an annular plate shape thrust bearing stationary member. Conducting holes passing through the thrust bearing stationary member are bored at center portions of herringbone dynamic pressure generating grooves at intervals of 120 degrees, and the conducting holes become supplying paths of the air outside when the conducting holes generates a lubricating function of a pump-out effect.
In both of Article 1 and Article 2, since as an electromagnetic switching valve shielding the conductive hole, a sensor detecting positive rotation and negative rotation, and a switch circuit switching open and closing operations of the electromagnetic switching valve by signal of the sensor are needed, there is a weak point that manufacturing cost is high and maintenance is needed comparing one direction rotation gas dynamic pressure bearing.
An object of the present invention is to provide a positive and negative rotation gas dynamic pressure bearing, a spindle motor, and a rotator device having a bearing construction generating a lubricating function of a pump-in effect increasing dynamic pressure at central portions of the dynamic pressure generating grooves taking in lubricating gas from both ends of the dynamic pressure generating grooves during rotation in one of positive and negative rotations, and during rotation of in the other of positive and negative rotations generating a lubricating function of a pump-out effect increasing dynamic pressure at both ends of the dynamic pressure generating grooves supplying lubricating gas to central portions of the dynamic pressure generating grooves through the conducting hole. Particularly, by rotating with the bearing movable member and by forming a self-switch valve opening and shutting the conducting hole taking in air depending on the rotation direction, the electromagnetic switching valve, the sensor, and the switch circuit are not needed. Dynamic pressures generating at dynamic pressure generating grooves equally arranged toward a circumference direction are all equal during rotation generating a lubricating function of a pump-in effect by that the self-switch valve shuts the conducting hole so as to decrease run out of rotation.
BRIEF SUMMARY OF THE INVENTION
The present invention is to provide a positive and negative rotation gas dynamic pressure bearing having a bearing stationary member and bearing movable member, and dynamic pressure generating grooves being equally arranged toward a circumference direction at one facing surface of one of the bearing stationary member and the bearing movable member, and further comprising: air taking holes formed in a wall of a valve case at nearly tangential angle about a circumference of the wall, an inner space of which is separated by a valve body freely coming up and down, so as to conduct all the time; an interconnected porosity bored at an upper side space of the valve body, and closed by the valve body during coming up of the valve; and self-switch valve rotating coaxially and in one body with the bearing movable member about the center of the valves, wherein each one end of a plural of independent conducting holes are equally arranged toward a circumference direction at an inner portion of the bearing movable member and corresponds to a position where high dynamic pressure of the same number of dynamic pressure generating grooves are equally arranged toward a circumference direction, and each other end of the independent conducting holes is closed during coming up and down of the valve body of the self-switch valve; and wherein the valve body of the self-switch valve closes the independent conducting hole when the bearing movable member rotates toward a rotation direction where a pump-in effect generating high dynamic pressure generates at central portions of dynamic pressure generating grooves, and the valve body of the self-switch valve opens the independent conducting hole so that lubricating gas is supplied to the central portions of the dynamic pressure generating grooves through the independent conducting hole during rotation of the bearing movable member toward a rotation direction where a pump-out effect generating high dynamic pressure generates at both ends of the central portions of the dynamic pressure generating grooves.
The present invention is to provide a spindle motor, wherein a spindle thereof is supported by a spindle supporting member through a positive and negative rotation gas dynamic pressure bearing, the positive and negative rotation gas dynamic pressure bearing having a bearing stationary member and a bearing movable member, forming dynamic pressure generating grooves being equally arranged toward a circumference direction at one facing surface among the bearing stationary member and the bearing movable member, and further comprising: air taking holes bored at a nearly tangential about a circumference wall of a valve case, an inner space of which is separated by a valve body freely coming up and down, so as to conduct all the time; and interconnected porosity bored at an upper side space of the valve body, and closed by the valve body during coming up of the valve; and a self-switch valve rotating coaxially and in one body with the bearing movable member about the center of the valve; wherein each one of a plurality of independent conducting holes are equally arranged toward a circumference direction at an inner porti
Adams & Wilks
Nguyen Hoa T.
Seiko Instruments Inc.
Watko Julie Anne
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