Spindle motor of a small-scale design
View Patent ↗The spindle motor described herein comprises a rotor having a rotor hub and a shaft connected to the rotor hub, a cylindrical bearing sleeve having a central bore to accommodate the shaft and a collar disposed at the receiving aperture, a cup-shaped bearing housing closed at one end to accommodate the bearing sleeve, a baseplate to hold the bearing receiving portion, a stopper ring disposed at the inside circumference of the rotor hub between the collar and the baseplate, and at least one radial bearing region formed between the outside diameter of the shaft and the inside diameter of the bore and defined by surface patterns. According to the invention, an annular axial bearing region is provided formed between a lower face of the collar and an upper face of the stopper ring. This design and construction makes it possible to realize spindle motors having small dimensions and, in particular, low overall heights.
1. A spindle motor of a small-scale design having a hydrodynamic bearing system which comprises:
a rotor ( 6 ) having a rotor hub ( 7 ) and a shaft ( 8 ) connected to the rotor hub;
a cylindrical bearing sleeve ( 10 ) having a central bore to receive the shaft ( 8 ) and a collar ( 11 ) disposed at a receiving aperture;
a baseplate ( 13 ) to hold a bearing receiving portion;
a stopper ring ( 14 ) disposed at the inside circumference of the rotor hub ( 7 ) between the collar ( 11 ) and the baseplate ( 13 ); and
at least one radial bearing region ( 15 , 16 ) formed between the outside diameter of the shaft and the inside diameter of the bore and defined by surface patterns ( 19 ), characterized by
a cup-shaped bearing housing ( 12 ) closed at one end to accommodate the bearing sleeve ( 10 );
an annular axial bearing region ( 18 ) formed between a lower face of the collar ( 11 ) and an upper face of the stopper ring ( 14 ), and
further characterized in that between the regions facing each other of the bearing housing ( 12 ) and the bearing sleeve ( 10 ), at least one fluid channel ( 24 ) is provided which connects a section ( 17 ) of the bearing gap between the bearing sleeve ( 10 ) and the shaft ( 8 ) to the end of a section ( 20 ), adjacent to the sealing region ( 23 ), of the bearing gap between the collar ( 11 ) and the stopper ring ( 14 ).
2. A spindle motor according to claim 1 , characterized in that the faces of the stopper ring ( 14 ) and/or of the collar ( 11 ) associated with the axial bearing region ( 18 ) have a surface pattern ( 19 ) which, on rotation of the rotor ( 6 ), generates a pumping action on the bearing fluid in the direction of the radial bearing region ( 15 , 16 ).
3. A spindle motor according to claim 1 , characterized in that a bearing gap ( 17 , 20 , 21 , 22 ) filled with a bearing fluid is provided, the bearing gap extending continuously between the respective surfaces facing each other of the bearing sleeve ( 10 ), the collar ( 11 ), the shaft ( 8 ), the rotor hub ( 7 ) and the stopper ring ( 14 ).
4. A spindle motor according to claim 3 , characterized in that a circular flow of bearing fluid is formed by the bearing gap ( 17 , 20 , 21 , 22 ) and the fluid channel ( 24 ).
5. A spindle motor according to claim 3 , characterized in that an annular gap ( 23 ) is provided between the outside diameter of the bearing housing ( 12 ) and the inside diameter of the stopper ring ( 14 ), the annular gap being connected to sections ( 17 , 20 ) of the bearing gap and narrowing in the direction of the bearing gap ( 17 , 20 ), and the gap being at least partially filled with bearing fluid and forming a reservoir for the bearing fluid as well as a capillary seal.
6. A spindle motor according to claim 1 , characterized in that a second annular axial bearing region ( 29 ) is formed between a lower face of the rotor hub ( 7 ) and an upper face of the collar ( 11 ).
7. A spindle motor according to claim 6 , characterized in that the surfaces of the rotor hub ( 7 ) and/or of the collar ( 11 ) associated with the second axial bearing region ( 29 ) have a surface pattern ( 19 ) which, on rotation of the rotor ( 6 ), generates a pumping action on the bearing fluid in the direction of radial bearing region ( 15 , 16 ).
8. A hard disk drive having a spindle motor ( 3 ) according to claim 1 to drive at least one storage disk ( 4 ) in rotation.