Hydrodynamic pressure bearing, spindle motor in which it is utilized, and disk-drive device furnished with the spindle motor

A hydrodynamic bearing comprising:

• a shaft defining a rotational center axis;
• a pair of annular thrust plates provided on, and projecting radially outward from, the outer circumferential surface of said shaft, said pair of thrust plates having an approximately conical form in which at least a portion of each said thrust plate shrinks in outer diameter with increasing separation from one of the axial faces of each said thrust plate, the outer peripheral surface of said portion therein formed in a sloping-face contour;
• a hollow round cylindrical sleeve in which are formed a radial inner-peripheral surface radially opposing the outer circumferential surface of said shaft via a micro-gap, and neighboring either end axially of said radial inner-peripheral surface, a stepped portion opposing both the outer circumferential surface of, and said one of the axial faces of, each said thrust plate;
• and
• ring-shaped members the inner peripheral surface of which is formed into a sloping-face contour such that heading toward its radially outward side from its inward side the inner diameter expands, one each fitted on an inner circumferential surface of each said stepped portion opposing the outer peripheral surface of said sloping-face contour of said thrust plate;
• wherein
• lubricant is retained, and pump-in spiral grooves through which dynamic pressure that acts heading radially inward is induced in said lubricant are formed, in between each said stepped portion and said one of the axial faces of each said thrust plate, whereby a pair of thrust bearing sections is configured,
• lubricant is retained in continuity with each said thrust bearing section, and herringbone grooves having an axially asymmetrical formation through which dynamic pressure that acts heading toward neighboring said thrust bearing sections is induced in said lubricant are formed, in between the outer circumferential surface of said shaft and said radial inner-peripheral surface of said sleeve, whereby a pair of radial bearing sections is configured,
• said lubricant retained in said radial bearing sections is divided axially by an air intervention formed in between the outer circumferential surface of said shaft and said radial inner-peripheral surface of said sleeve,
• said air intervention opens to outside air through a communicating passage provided in said shaft,
• a pair of taper seal sections that, with respect to the rotational center axis, each slope heading toward its radially inward side from its outward side, and whose gap clearance dimension gradually expands with increasing separation from said thrust bearing section, is formed in between each said ring-shaped member and said approximately conical form of each thrust plate, and
• said lubricant retained in each said thrust bearing section forms an interface within each said taper seal section.

A hydrodynamic bearing comprising:

• a shaft defining a rotational center axis;
• a pair of annular thrust plates provided on, and projecting radially outward from, the outer circumferential surface of said shaft, said pair of thrust plates having an approximately conical form in which at least a portion of each said thrust plate shrinks in outer diameter with increasing separation from one of the axial faces of each said thrust plate, the outer peripheral surface of said portion therein formed in a sloping-face contour inclining at an angle of 20 to 35 degrees with respect to the rotational center axis;
• a hollow round cylindrical sleeve in which are formed a radial inner-peripheral surface radially opposing the outer circumferential surface of said shaft via a micro-gap, and neighboring either end axially of said radial inner-peripheral surface, a stepped portion opposing both the outer circumferential surface of, and said one of the axial faces of, each said thrust plate;
• and
• ring-shaped members the inner peripheral surface of which is formed into a sloping-face contour inclining at an angle of 15 to 30 degrees with respect to the rotational center axis such that heading toward its radially outward side from its inward side the inner diameter expands, one each fitted on an inner circumferential surface of each said stepped portion opposing the outer peripheral surface of said sloping-face contour of said thrust plate;
• wherein
• lubricant is retained, and pump-in spiral grooves through which dynamic pressure that acts heading radially inward is induced in said lubricant are formed, in between each said stepped portion and said one of the axial faces of each said thrust plate, whereby a pair of thrust bearing sections is configured,
• lubricant is retained in continuity with each said thrust bearing section, and herringbone grooves having an axially asymmetrical formation through which dynamic pressure that acts heading toward neighboring said thrust bearing sections is induced in said lubricant are formed, in between the outer circumferential surface of said shaft and said radial inner-peripheral surface of said sleeve, whereby a pair of radial bearing sections is configured,
• said lubricant retained in said radial bearing sections is divided axially by an air intervention formed in between the outer circumferential surface of said shaft and said radial inner-peripheral surface of said sleeve,
• said air intervention opens to outside air through a communicating passage provided in said shaft,
• a pair of taper seal sections that, with respect to the rotational center axis, each slope heading toward its radially inward side from its outward side at an angle of 2 to 15 degrees with respect to the rotational center axis, and whose gap clearance dimension gradually expands with increasing separation from said thrust bearing section, is formed in between each said ring-shaped member and said approximately conical form of each thrust plate, and
• said lubricant retained in each said thrust bearing section forms an interface within each said taper seal section.

A hydrodynamic bearing comprising:

• a shaft defining a rotational center axis;
• an annular thrust plate provided on, and projecting radially outward from, the outer circumferential surface of said shaft, said thrust plate having an approximately conical form in which at least a portion of said thrust plate shrinks in outer diameter with increasing separation from one of the axial faces of said thrust plate, the outer peripheral surface of said portion therein formed in a sloping-face contour inclining at an angle of 20 to 35 degrees with respect to the rotational center axis;
• a hollow round cylindrical sleeve in which are formed a stepped portion opposing both the outer circumferential surface of, and said one of the axial faces of, said thrust plate, and continuous with said stepped portion, a radial inner-peripheral surface radially opposing the outer circumferential surface of said shaft via a micro-gap;
• and
• a ring-shaped member the inner peripheral surface of which is formed into a sloping-face contour inclining at an angle of 15 to 30 degrees with respect to the rotational center axis such that heading toward its radially outward side from its inward side the inner diameter expands, fitted on an inner circumferential surface of said stepped portion opposing the outer peripheral surface of said sloping-face contour of said thrust plate;
• wherein
• lubricant is retained, and dynamic-pressure-generating grooves for inducing dynamic pressure in said lubricant are provided, in between the outer circumferential surface of said shaft and the radial inner-peripheral surface of said sleeve, whereby a radial bearing section is configured,
• lubricant is retained, and dynamic-pressure-generating grooves for inducing dynamic pressure in said lubricant are provided, in between said stepped portion and said one of the axial faces of said thrust plate, whereby a thrust bearing section is configured,
• a taper seal section that, with respect to the rotational center axis, slopes heading toward its radially inward side from its outward side at an angle of 2 to 15 degrees with respect to the rotational center axis, and whose gap clearance dimension gradually expands with increasing separation from said thrust bearing section, is formed in between said ring-shaped member and said approximately conical form of the thrust plate, and
• said lubricant retained in said thrust bearing section forms an interface within said taper seal section.

A spindle motor comprising:

• a base member;
• a shaft one end portion of which is fixed to said base member, said shaft defining a rotational center axis;
• an annular thrust plate provided on, and projecting radially outward from, the outer circumferential surface of said shaft, said thrust plate having an approximately conical form in which at least a portion of said thrust plate shrinks in outer diameter with increasing separation from one of the axial faces of said thrust plate, the outer peripheral surface of said portion therein formed in a sloping-face contour;
• a hollow round cylindrical sleeve in which are formed a stepped portion opposing both the outer circumferential surface of, and said one of the axial faces of, said thrust plate, and continuous with said stepped portion, a radial inner-peripheral surface radially opposing the outer circumferential surface of said shaft via a micro-gap;
• a rotor hub that rotates together with said sleeve;
• and
• a ring-shaped member the inner peripheral surface of which is formed into a sloping-face contour such that heading toward its radially outward side from its inward side the inner diameter expands, fitted on an inner circumferential surface of said stepped portion opposing the outer peripheral surface of said sloping-face contour of said thrust plate;
• wherein
• lubricant is retained, and dynamic-pressure-generating grooves for inducing dynamic pressure in said lubricant are provided, in between the outer circumferential surface of said shaft and the radial inner-peripheral surface of said sleeve, whereby a radial bearing section is configured,
• lubricant is retained, and dynamic-pressure-generating grooves for inducing dynamic pressure in said lubricant are provided, in between said stepped portion and said one of the axial faces of said thrust plate, whereby a thrust bearing section is configured,
• a taper seal section that, with respect to the rotational center axis, slopes heading toward its radially inward side from its outward side, and whose gap clearance dimension gradually expands with increasing separation from said thrust bearing section, is formed in between said ring-shaped member and said approximately conical form of the thrust plate, and
• said lubricant retained in said thrust bearing section forms an interface within said taper seal section.

A disk-drive device including:

• a housing interiorly in which a clean chamber is formed;
• a spindle motor accommodated within the interior of said housing, for driving a data-recording disk;
• and
• an information accessing means for writing information into and reading information from requisite locations on said data-recording disk;
• the disk-drive device characterized in that said spindle motor comprises a base member;
• a shaft one end portion of which is fixed to said base member, said shaft defining a rotational center axis;
• an annular thrust plate provided on, and projecting radially outward from, the outer circumferential surface of said shaft, said thrust plate having an approximately conical form in which at least a portion of said thrust plate shrinks in outer diameter with increasing separation from one of the axial faces of said thrust plate, the outer peripheral surface of said portion therein formed in a sloping-face contour;
• a hollow round cylindrical sleeve in which are formed a stepped portion opposing both the outer circumferential surface of, and said one of the axial faces of, said thrust plate, and continuous with said stepped portion, a radial inner-peripheral surface radially opposing the outer circumferential surface of said shaft via a micro-gap;
• a rotor hub on which said data recording disk is carried, said rotor hub rotating together with said sleeve;
• and a ring-shaped member the inner peripheral surface of which is formed into a sloping-face contour such that heading toward its radially outward side from its inward side the inner diameter expands, fitted on an inner circumferential surface of said stepped portion opposing the outer peripheral surface of said sloping-face contour of said thrust plate;
• wherein
• lubricant is retained, and dynamic-pressure-generating grooves for inducing dynamic pressure in said lubricant are provided, in between the outer circumferential surface of said shaft and the radial inner-peripheral surface of said sleeve, whereby a radial bearing section is configured,
• lubricant is retained, and dynamic-pressure-generating grooves for inducing dynamic pressure in said lubricant are provided, in between said stepped portion and said one of the axial faces of said thrust plate, whereby a thrust bearing section is configured,
• a taper seal section that, with respect to the rotational center axis, slopes heading toward its radially inward side from its outward side, and whose gap clearance dimension gradually expands with increasing separation from said thrust bearing section, is formed in between said ring-shaped member and said approximately conical form of the thrust plate, and
• said lubricant retained in said thrust bearing section forms an interface within said taper seal section.