Spindle motor

A spindle motor comprising, in combination:

• a cylinder of a radial hydrodynamic gas bearing having radial hydrodynamic grooves formed in an outer circumferential surface thereof;
• a disk of a thrust hydrodynamic gas bearing having thrust hydrodynamic grooves formed in an upper face thereat the cylinder and the disk being disposed on an upper end on an axial center of a stator core having a stator around which a motor coil is wound;
• a hollow cylinder having a smooth inner surface positioned on an inner surface of a hub acting as a rotational member to face the cylinder of the radial hydrodynamic gas bearing;
• and
• a rotor magnet disposed on said hub to face the stator motor coil,
• wherein a load in a radial direction is supported by the radial hydrodynamic gas bearing,
• wherein a load in a thrust direction is supported by using the thrust hydrodynamic gas bearing together with a magnetic bearing consisting of the stator and the rotor magnet, and
• wherein said rotor magnet and said motor coil are configured, in combination, to magnetically balance a weight of at least said hub and said hollow cylinder and said rotor magnet attached thereto so as to maintain a first clearance between said disk thrust hydrodynamic grooves and a bottom surface of said hollow cylinder in a static state and to maintain a second clearance between said disk thrust hydrodynamic grooves and said bottom surface of said hollow cylinder in a dynamic steady-state condition.

A spindle motor comprising, in combination:

• a hub acting as a rotational member disposed on an upper end of a motor shaft provided with a rotor magnet disposed about an outer circumferential surface thereof;
• a disk of a trust hydrodynamic gas bearing having thrust hydrodynamic grooves formed in a lower face thereof, a cylinder of a radial hydrodynamic gas bearing having radial hydrodynamic grooves formed in an outer circumferential surface thereof, the disk and the cylinder being disposed below the motor shaft in a fixed relation thereto,
• a hollow cylinder having a smooth inner surface positioned to face the cylinder of the radial hydrodynamic gas bearing and positioned so that a top surface of the hollow cylinder faces the disk thrust hydrodynamic grooves, and
• a stator around which the motor coil is wound, the stator facing the rotor magnet, the hollow cylinder and the stator being disposed in a case as a fixed member,
• wherein a load in a radial direction is supported by the radial hydrodynamic gas bearing, and
• wherein a load in a thrust direction is supported by using the thrust hydrodynamic gas bearing together with a magnetic bearing consisting of the stator and the rotor magnet,
• wherein said rotor magnet and said motor coil are configured, in combination, to magnetically balance a weight of at least said hub and said motor shaft, said disk, and said cylinder attached thereto so as to maintain a first clearance between said disk thrust hydrodynamic grooves and a top surface of said hollow cylinder in a static state and to maintain a second clearance between said disk thrust hydrodynamic grooves and said top surface of said hollow cylinder in a dynamic steady-state condition.