Hydrodynamic fluid pressure bearings

A motor comprising:

• a shaft;
• a cylindrical sleeve for receiving and supporting said shaft for relative rotation of the shaft and the cylindrical sleeve, the shaft and sleeve respectively having an outer cylindrical surface having at least one annular recess and an inner cylindrical surface which oppose each other to form a clearance gap around said shaft, the sleeve member being provided with a communication hole to the external atmosphere, and the inner cylindrical surface of the sleeve forming an axially extending storage groove thereon;
• a cup-shaped member having a cylindrical portion, said cup-shaped member being secured to an upper end portion of said shaft;
• a magnet secured to an inner cylindrical surface of said cup-shaped member;
• a stator core fixed to an outside of said sleeve;
• at least one of inner and outer surfaces of respective said sleeve and said shaft having at least one pressure generating groove in said clearance gap;
• an inner end portion of said shaft having a support member for supporting the shaft against a thrust load;
• and
• a bearing liquid filling in said clearance gap, the bearing liquid being provided at an upper portion of the clearance gap above the recess and at a lower portion of the clearance gap below the recess, the bearing liquid at the upper and lower portions of the clearance gap being separated from one another at the recess to form a gas space for reducing viscosity of the bearing liquid between the shaft and the cylindrical sleeve, the storage groove communicating the bearing liquid by capillary action from one of the lower and upper portions of the clearance gap to the other portion of said gap, and the communication hole connecting the gas space to the outer atmosphere.

A hydrodynamic bearing structure for supporting a rotator carrying a load for rotating, said hydrodynamic bearing structure comprising:

• a shaft member having an outer bearing surface defining at least one annular recess;
• a cylindrical sleeve member for receiving and supporting said shaft member for relative rotation of the shaft member and the cylindrical sleeve member, the sleeve member having an inner bearing surface provided with an axially extending storage groove thereon, and having a communication hole to the external atmosphere;
• a bearing gap formed in a clearance between said inner bearing surface and said outer bearing surface and a bearing liquid in said bearing gap;
• at least one bearing groove for generating a hydrodynamic pressure in said bearing liquid formed on at least one surface of said inner and outer bearing surfaces;
• and
• a supporting member for supporting the shaft member against a thrust load, the bearing liquid being provided at an upper portion of the bearing gap above the recess and at a lower portion of the bearing gap below the recess, the bearing liquid at the upper and lower portions of the bearing gap being separated from one another at the recess to form a gas space for reducing viscosity resistance of the bearing liquid between the shaft member and the sleeve member, the storage groove communicating the bearing liquid by capillary action from one of the lower and upper portions of the bearing gap to the other portion of said gap, and the communication hole connecting the gas space to the outer atmosphere.

A motor comprising:

• a shaft;
• a sleeve for receiving said shaft to allow relative rotation of the shaft and the sleeve, the shaft and the sleeve defining a gap therebetween, an axially extending storage groove formed on one of the shaft and the sleeve;
• a hydrodynamic fluid filling the gap;
• a hydrodynamic pressure groove and an atmosphere vent hole formed on one of the shaft and the sleeve for causing a hydrodynamic pressure in the fluid during relative rotation of the shaft and the sleeve;
• and
• a hydrodynamic bearing structure including an annular recess formed on at least one of the shaft and the sleeve on a surface that confronts the gap, the recess extending around the shaft to form an enlarged space in the gap to separate the hydrodynamic fluid, said hydrodynamic fluid being provided at an upper portion of the gap above the recess and at a lower portion of the gap below the recess, the hydrodynamic fluid at the upper and lower portions of the gap being separated from one another at the enlarged space for reducing viscosity of the hydrodynamic fluid between the shaft and the sleeve, the storage groove communicating the hydrodynamic fluid by capillary action from one of the lower and upper portions of the gap to other portion of the gap, and the vent-hole connecting the enlarged space to the outer atmosphere.

A hydrodynamic bearing construction for an electric motor comprising:

• a shaft;
• a sleeve member for relatively rotatably receiving the shaft, the shaft and the sleeve member cooperating to form a clearance gap between the shaft and the sleeve member;
• a bearing liquid filling the gap;
• means for causing dynamic pressure in the liquid during the relative rotation of the shaft and the sleeve member in order to support the shaft and the sleeve member;
• means for forming an annular space in the gap to separate the bearing liquid thereat;
• and
• means for partially communicating the separated liquid.