Disk drive device having fluid dynamic bearing with porous member at position in which lubricant is charged
A disk drive device includes a fixed body section, a rotating body section, a bearing unit and a drive unit. The bearing unit includes a shaft that is a rotation center, a sleeve that has an accommodating portion in which the shaft is accommodated and that permits relative rotation around the shaft, a radial space defined by an inner wall surface of the sleeve-accommodating portion and an outer wall surface of the shaft, first and second radial dynamic pressure grooves that generate a radial dynamic pressure in at least one of the inner wall surface of the sleeve and the outer wall surface of the shaft that define the radial space, a lubricant charged into the radial space, and a porous filter that is disposed in at least a portion of the charging space in which the lubricant is charged, for capturing foreign matter contained in the lubricant.
1. A disk drive device, comprising
a base member;
a bearing unit that is disposed in the base member and that rotatably supports a recording disk with respect to the base member; and
a drive unit configured to rotationally drive the recording disk supported by the bearing unit,
the bearing unit including:
a shaft that is a center of rotation;
a sleeve that has an accommodating portion in which the shaft is accommodated and that is configured to permit relative rotation around the shaft;
a radial space defined by an inner wall surface of the accommodating portion of the sleeve and an outer wall surface of the shaft;
a radial dynamic pressure groove configured to generate a radial dynamic pressure and formed in at least one of the inner wall surface of the sleeve and the outer wall surface of the shaft that define the radial space;
a lubricant charged into the radial space; and
a porous member that is disposed in at least a portion of a charging space into which the lubricant is charged, for capturing foreign matter contained in the lubricant;
wherein
the porous member is a filter of a multi-layer structure, and
a density of the filter is varied from a rough state to a dense state in correspondence with a moving direction of foreign matter contained in the lubricant.
2. The disk drive device according to claim 1 , wherein the porous member includes sintered metal.
3. The disk drive device according to claim 1 , wherein the porous member includes at least a first layer and a second layer,
the first layer being configured to allow foreign matter having a size less than 0.5 μm to pass therethrough, whereas the first layer is configured to capture foreign matter of a size of 1.0 μm or greater, and the second layer captures foreign matter of a size of 0.3 μm or greater.
4. The disk drive device according to claim 1 , wherein
an end of the radial space is in communication with a capillary seal, and
a cover member covering at least a portion of an opened end of the capillary seal is disposed outside the opened end.
5. The disk drive device according to claim 1 , wherein at least one of the inner wall surface of the sleeve and the outer wall surface of the shaft is made of SIALON ceramic.
6. The disk drive device according to claim 1 , wherein
the sleeve includes a circulation path through which the lubricant circulates in a direction along the shaft, and
the porous member is disposed within the circulation path.
7. A disk drive device, comprising:
a base member;
a bearing unit that is disposed in the base member and that rotatably supports a recording disk with respect to the base member; and
a drive unit configured to rotationally drive the recording disk supported by the bearing unit,
the bearing unit including:
a shaft that is a center of rotation;
a sleeve that has an accommodating portion in which the shaft is accommodated and that is configured to permit relative rotation around the shaft;
a radial space defined by an inner wall surface of the accommodating portion of the sleeve and an outer wall surface of the shaft;
a radial dynamic pressure groove configured to generate a radial dynamic pressure and formed in at least one of the inner wall surface of the sleeve and the outer wall surface of the shaft that define the radial space;
a lubricant charged into the radial space; and
a porous member that is disposed in at least a portion of a charging space into which the lubricant is charged, for capturing foreign matter contained in the lubricant;
wherein the porous member is made of nonwoven fabric.
8. The disk drive device according to claim 7 , wherein
the porous member is a filter of a multi-layer structure, and
a density of the filter is varied from a rough state to a dense state in correspondence with a moving direction of foreign matter contained in the lubricant.
9. The disk drive device according to claim 7 , wherein the porous member includes at least a first layer and a second layer,
the first layer being configured to allow foreign matter having a size less than 0.5 μm to pass therethrough, whereas the first layer is configured to capture foreign matter of a size of 1.0 μm or greater, and the second layer is configured to capture foreign matter of a size of 0.3 μm or greater.
10. The disk drive device according to claim 7 , wherein
an end of the radial space is in communication with a capillary seal, and
a cover member covering at least a portion of an opened end of the capillary seal is disposed outside the opened end.
11. The disk drive device according to claim 7 , wherein at least one of the inner wall surface of the sleeve and the outer wall surface of the shaft is made of SIALON ceramic.
12. The disk drive device according to claim 7 , wherein
the sleeve includes a circulation path through which the lubricant circulates in a direction along the shaft, and
the porous member is disposed within the circulation path.