Parallel capillary seal for a disk drive

#The present invention relates to the field of fluid dynamic bearing assemblies, and more specifically to improved apparatus for sealing the improved fluid dynamic bearing from the outside atmosphere.

#Disc drive memory systems have been used in computers for many years for storage of digital information. Information is recorded on concentric memory tracks of a magnetic disc medium, the actual information being stored in the form of magnetic transitions within the medium. The discs themselves are rotatably mounted on a spindle, the information being accessed by means of transducers located on a pivoting arm which moves radially over the surface of the disc. The read/write heads or transducers must be accurately aligned with the storage tracks on the disc to ensure proper reading and writing of information; thus the discs must be rotationally stable.

#During operation, the discs are rotated at very high speeds within an enclosed housing by means of an electric motor which is generally located inside the hub or below the discs. One type of motor in common use is known as a spindle motor. Such motors typically have a spindle mounted by means of two ball bearing systems to a motor shaft disposed in the hub. One of the bearings is typically located near the top of the spindle, and the other near the bottom. These bearings allow for rotational movement between the shaft and hub, while maintaining accurate alignment of the spindle to the shaft. The bearings themselves are normally lubricated by grease or oil.

#FIG. 1 is an exploded perspective view of a disc drive in which a motor incorporating the present seal design is useful;

#FIG. 2 is a vertical section of a motor incorporating the journal bearing and seal as known in the prior art;

#FIG. 3A is a detailed vertical section of a portion of the motor illustrated in FIG. 2;

#The description to follow of a preferred embodiment or embodiments of the present invention teaches a highly efficient apparatus and method for sealing the counterplate without the need for welding in a hydrodynamic bearing motor. The technique is especially useful in thrust plate design hydrodynamic bearings incorporated in spindle motors for use in a disc drive, as the loss of fluid from the dynamic bearing or any outgassing from materials to use to seal the dynamic bearing is especially undesirable in such an environment. However, the present invention has many other uses that in motors for hard disc drives, and is not intended to be limited to uses in such environment. The invention has other uses, because the preservation of the fluid level in a fluid dynamic bearing is always a critical feature to provide long life for the fluid dynamic bearing. However, it is especially useful in hard disc drives because of the importance of not having any fluid leak out of the bearing or motor or expelled from the bearing over the entire life of the bearing, as contamination of the atmosphere within the hard disc drive by droplets are outgassing is especially undesirable.

#The basic principles of the invention will be explained with respect to a hydrodynamic bearing used in a spindle motor such as is used in the disc drive shown in the exploded view of FIG. 1, the spindle motor itself being shown in the vertical sectional view of FIG. 2. FIG. 1 shows a disc drive 100 including a base 110, a cover 115, and a sealing ring 120 which may be used to seal the two together to provide a sealed environment for the disc drive.

#A spindle motor generally indicated at 130 and to be described in detail below includes a hub which supports one or more discs 140 for rotation at constant speed. Each of these discs has one or both surfaces comprising a plurality of tracks on which data is stored. An actuator generally indicated at 150 supports a plurality of actuator arms, each having a transducer at an end thereof which is associated with the disc storage surface. As the disc rotates, the transducer flies on a thin cushion of air over the surface of the disc and reads and writes data to and from tracks on the disc. It is essential to the long lived operation of the motor which must rotate at high speed and at constant speed for hours at a time and maintain that on a daily basis for years at a time that the fluid be maintained in the gaps which define the hydrodynamic bearings and which in turn support the hub, and the discs it carries for rotation. Thus it is essential that some apparatus and method be adopted for sealing the fluid dynamic bearing from the outside atmosphere. This prevents contamination of that atmosphere and loss of the fluid which is so essential to the long life of the hydrodynamic bearings.