Oil filling seal for hydrodynamic motor utilizing a movable sealing element

DETAILED DESCRIPTION It is therefore an objective of the present invention to provide a fill technique for hydrodynamic bearings which is simple and reliable and adaptable to mass production techniques.
It is a further objective to provide such a process which results on a repeatable basis of the injection of the desired amount of oil or other fluid into the hydrodynamic bearing without entrapping any bubbles into the fluid.
A further objective of the invention is to provide a method and apparatus for sealing an end of the motor while the fluid is added to a motor or bearing cartridge using a rotating shaft.
These and other objectives of the present invention are accomplished by assembling the rotating shaft motor or cartridge and incorporating an o-ring which surrounds the rotating shaft and is borne on a carrier.
As supported on the carrier, the o-ring does not normally block the bearing passages which would prevent the smooth distribution of oil throughout the motor.
However, the carrier and o-ring combination are designed to allow the o-ring to be forced into place between the rotatable hub shaft and sleeve for completely sealing the remaining portion of the bearing during filling.
The rotating shaft itself includes a central reservoir, having one or more grooves or passages communicating with the hydrodynamic bearing surfaces and ending in a septum or rubber plug which is inserted in the bottom of the shaft.
To fill the hydrodynamic bearing, the o-ring is pressed into place, an oil filling needle is inserted through the septum, and the motor is filled with a lubricating fluid in a vacuum chamber.
Typically, the motor, needle and a container for oil are placed in a vacuum chamber which is evacuated.
The resulting pressure differential causes the air within the motor to exit through the needle and up through the oil.
After the air is withdrawn from the motor, the vacuum chamber pressure is slowly returned to ambient pressure, causing oil to flow up through the needle into a vacuum which is now created in the bearing