Metal working – Method of mechanical manufacture – Process for making bearing or component thereof
Reexamination Certificate
1999-08-25
2001-03-06
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Process for making bearing or component thereof
C384S112000, C384S123000, C082S001110
Reexamination Certificate
active
06195895
ABSTRACT:
TECHNICAL FIELD
The present invention relates to, but is not limited to, the configuration of a hydrodynamic thrust bearing for use in a computer hard disc drive spindle motor assembly.
BACKGROUND OF THE INVENTION
Computer hard disc drives generally comprise an array of magnetic discs mounted to a spindle motor assembly. Data is written to, and read from, each magnetic disc by means of a read/write head located at the end of an arm which extends between the discs. Positioning of the arm is accomplished by means of a voice coil motor under the control of disc drive control electronics.
The array of magnetic discs is mounted to a hub of the spindle motor assembly. The hub is mounted for rotation with respect to a base of the spindle motor assembly by means of a bearing arrangement. In use, the hub is rotated by means of an electromagnetic motor.
The bearing arrangement is expected to have a long, maintenance-free service life. In this regard, the amount of bearing fluid in the hydrodynamic bearing is chosen carefully; if there is too much bearing fluid in the bearing arrangement, some of it may leak out and contaminate other areas of the disc drive, while too little bearing fluid may result in the bearing arrangement seizing.
If the correct amount of bearing fluid is provided, it is important to ensure that leakage of bearing fluid from the bearing arrangement over the life of the motor is minimized. Any such leakage will have the consequence firstly of potentially contaminating the disc drive and secondly, of reducing the amount of bearing fluid below the ideal amount, potentially causing bearing arrangement failure.
Accordingly, it would be desirable to have a hydrodynamic bearing configuration in which bearing fluid leakage is reduced.
SUMMARY OF THE INVENTION
According to the invention there is provided a hydrodynamic bearing arrangement comprising:
a journal defining a journal bore and defining a recess at an end of the journal bore for receiving a thrust plate, the journal further defining a land around the recess and defining a seal groove around the land for receiving a seal;
a shaft mounted in the journal bore;
a thrust plate extending transversely from the shaft and being located in the recess defined by the journal;
a seal located in the seal groove; and
a counter plate mounted to the journal in abutting relationship with the seal and a surface of the land, and being located adjacent to the thrust plate,
the bearing arrangement having a passage defined therein between the recess and the seal groove, for permitting the removal of air from the seal groove to the recess.
Also according to the invention there is provided a hydrodynamic bearing journal for a computer disc drive, the journal defining:
a journal bore for receiving a shaft;
a recess at an end of the journal bore for receiving a thrust plate;
a land around the recess, the land having an upper surface against which a counter plate abuts in use; and
a seal groove around the land for receiving a seal;
wherein the upper surface of the land has a groove defined therein for permitting the removal of any from the seal groove to the recess after assembly of the counter plate to the journal.
Further according to the invention there is provided a method of manufacturing a hydrodynamic bearing journal comprising the steps of:
forming a recess in one end of the journal for receiving a thrust plate;
forming a land around the recess, the land having an upper surface against which a counter plate abuts in use;
forming a seal groove around the land, for receiving a seal; and
forming a groove in the upper surface of the land for permitting the removal of air from the seal groove to the recess after assembly of the counter plate to the journal.
Preferably, the forming steps are performed by turning the journal in a lathe, and the step of forming the groove in the upper surface of the land comprises the steps of:
rotating the journal in a chuck of the lathe;
positioning a cutting tool adjacent to the upper surface of the land with a cutting portion of the tool located below the surface of the land; and
traversing the cutting tool across the land to form the groove in a spiral shape in the upper surface of the land.
Other features of the present invention, as well as the advantages of providing a means for removing air from the seal groove, are disclosed or apparent in the section entitled: “BEST MODE FOR CARRYING OUT THE INVENTION.”
REFERENCES:
patent: 5694268 (1997-12-01), Dunfield et al.
Addy Roger
Wuester, Sr. David
Butler Marc W.
Hughes S. Thomas
LaRiviere Grubman & Payne, LLP
Seagate Technology LLC
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