The invention relates to a spindle motor, particularly for the purpose of driving the platters in hard disk drives having a baseplate, a stator arrangement that is stationary with respect to the baseplate, a shaft and a bearing system to rotatably support a rotary driven rotor connected to the shaft. In order to create a spindle motor in which it is possible to connect the shaft to the rotor with a high holding force and improved running precision, provision is made according to the invention for the shaft to be at least partly formed as a hollow shaft and for the rotor to have a shaft shoulder aligned concentric to its rotational axis which is inserted into the hollow shaft and firmly connected to the shaft.
1. A spindle motor, particularly for the purpose of driving platters in hard disk drives, comprising:
a base plate;
a stator arrangement that is stationary with respect to the base plate;
a shaft and a hydrodynamic bearing system on which a rotary driven rotor connected to the shaft is rotatably supported, the hydrodynamic bearing system including a liquid lubricant;
the shaft being formed at least partly as a hollow shaft and the rotor having a shaft shoulder aligned concentrically to its rotational axis, said shoulder disposed within and firmly fixed to the shaft;
said bearing system comprising at least one radial bearing region formed by an outer surface of said shaft and a bearing sleeve having an inner surface surrounding said shaft, said bearing system further comprising a thrust bearing formed by a thrust plate arranged at a lower end of the hollow shaft and a covering plate;
said thrust plate and said hollow shaft constituting a monolithic element.
2. A spindle motor according to claim 1 , characterized in that the connection between the shaft shoulder and the hollow shaft is an interference fit.
3. A spindle motor according to claim 1 , characterized in that the connection between the shaft shoulder and the hollow shaft is a bonded connection.
4. A spindle motor according to claim 1 , characterized in that the shaft shoulder is a monolithic part of the rotor.
5. A spindle motor according to claim 1 , characterized in that the shaft shoulder is a monolithic part of the rotor.
6. A spindle motor, particularly for the purpose of driving platters in hard disk drives, comprising:
a base plate;
a stator arrangement that is stationary with respect to the base plate;
a shaft and a hydrodynamic bearing system on which a rotary driven rotor connected to the shaft is rotatably supported, the hydrodynamic bearing system including a liquid lubricant;
the shaft being formed at least partly as a hollow shaft and the rotor having a shaft shoulder aligned concentrically to its rotational axis, said shoulder disposed within and firmly fixed to the shaft;
said bearing system comprising at least one radial bearing region formed by an outer surface of said shaft and a bearing sleeve having an inner surface surrounding said shaft, said bearing system further comprising a thrust bearing formed by a thrust plate arranged at a lower end of the hollow shaft and a covering plate;
said thrust plate constituting a monolithic element with a plug that is inserted into the hollow shaft and firmly connected to the hollow shaft.
7. A spindle motor according to claim 6 , characterized in that the connection between the plug and the hollow shaft is an interference fit.
8. Spindle motor according to claim 6 , characterized in that the connection between the plug and the hollow shaft is a bonded connection.
9. A spindle motor according to claim 6 , characterized in that the rotor shaft shoulder is a monolithic part of the rotor.