Self-pressure-balanced hydrodynamic bearing spindle motor

A spindle motor having hydrodynamic bearings surrounding a shaft, said motor comprising:

• (a) a thrust bearing plate perpendicular to said shaft;
• (b) a first set of circulation channels in said shaft, said first set of circulation channels positioned above said thrust bearing plate;
• (c) a second set of circulation channels in said shaft, said second set of circulation channels positioned below said thrust bearing plate;
• (d) a shaft bore in said shaft;
• and
• (e) both said first set of circulation channels and said second set of circulation channels crossing said shaft bore;
• (f) wherein said circulation channels and said shaft bore together allow flow of lubricating fluid.

A spindle motor having hydrodynamic bearings, said motor comprising:

• (a) a shaft having a longitudinal axis;
• (b) a radial thrust bearing plate perpendicular to said shaft and centrally positioned on said longitudinal axis of said shaft;
• (c) an annular insert surrounding said shaft above said thrust bearing plate and an annular sleeve surrounding said shaft below said thrust bearing plate;
• (d) an upper axial cavity formed between said shaft and said annular insert and a lower axial cavity formed between said shaft and said annular sleeve;
• (e) a first set of circulation channels in said shaft positioned above said thrust bearing plate and a second set of circulation channels in said shaft positioned below said thrust bearing plate;
• (f) a shaft bore in said shaft, both said first set of circulation channels and said second set of circulation channels crossing said shaft bore;
• and
• (g) an annular compensation slot formed in said insert and surrounding said shaft;
• (h) wherein said circulation channels, said shaft bore, and said compensation slot together allow lubricating fluid to flow between said upper axial cavity and said lower axial cavity.

A spindle motor having hydrodynamic bearings, said motor comprising:

• (a) a shaft having a longitudinal axis;
• (b) a first radial surface substantially perpendicular to said shaft;
• (c) a second radial surface substantially perpendicular to said shaft;
• (d) said first radial surface at least partially coextensive to said second radial surface;
• and
• (e) a face seal formed between said first radial surface and said second radial surface, said face seal being a capillary seal when said motor is in a static state.

A spindle motor having hydrodynamic bearings, said motor comprising:

• (a) a shaft having a radial thrust bearing plate substantially perpendicular to said shaft, said thrust bearing plate having upper and lower radial plate surfaces, said shaft having a shaft outer diameter and a longitudinal axis;
• (b) an insert having an insert inner diameter and a lower radial insert surface substantially perpendicular to said insert inner diameter, said insert inner diameter surrounding said shaft outer diameter above said thrust bearing plate to form an upper axial cavity therebetween, said lower radial insert surface being at least partially coextensive with said upper radial plate surface;
• (c) a sleeve having a sleeve inner diameter and a radial sleeve support surface substantially perpendicular to said sleeve inner diameter, said sleeve inner diameter surrounding said shaft outer diameter below said thrust bearing plate to form a lower axial cavity therebetween, said radial sleeve support surface being at least partially coextensive with said lower radial plate surface;
• (d) said thrust bearing plate being substantially centrally positioned along said longitudinal axis of said shaft;
• (e) an annular end cap having a lower radial cap surface and a cap outer diameter;
• (f) said insert having an insert outer diameter and an upper radial insert surface, said upper radial insert surface at least partially coextensive with said lower radial cap surface;
• (g) said sleeve having an upper sleeve inner diameter surrounding said cap outer diameter and said insert outer diameter;
• and
• (h) an annular z-slot formed below said lower radial cap surface and between said sleeve inner diameter and said insert outer diameter.

A method for constructing a spindle motor having hydrodynamic bearings and a shaft with a centrally located radial thrust bearing plate, said method comprising the steps of:

• (a) positioning a sleeve within a motor, said sleeve having a sleeve inner diameter and a radial sleeve support surface substantially perpendicular to said sleeve inner diameter;
• (b) inserting a shaft into said sleeve, said shaft having a radial thrust bearing plate substantially perpendicular to said shaft, said thrust bearing plate having upper and lower radial plate surfaces, said shaft having a shaft outer diameter and a longitudinal axis, said thrust bearing plate being substantially centrally positioned along said longitudinal axis of said shaft;
• (c) forming a lower axial cavity between said sleeve inner diameter and said shaft outer diameter below said thrust bearing plate;
• (d) positioning an annular insert within said sleeve and around said shaft, said insert having an insert inner diameter and a lower radial insert surface substantially perpendicular to said insert inner diameter, said lower radial insert surface being at least partially coextensive with said upper radial plate surface;
• (e) forming an upper axial cavity between said insert inner diameter and said shaft outer diameter above said thrust bearing plate.