Patent ID: 7528526

Claim:
A piezoelectric drive unit for generating a rotating drive movement comprising: a stator ( 1 ), a rotor ( 2 , 5 , 7 ) rotatable about a rotational axis ( 11 ) with respect to the stator, and drive elements taking the form of several piezoelectric actuators ( 8 ), an annular gap ( 4 ′) filled with a fluid medium ( 10 ) that is formed between the facing surfaces of the stator ( 1 ) and the rotor ( 2 , 5 , 7 ),a plurality of piezoelectric actuators ( 8 a - 8 f ) arranged adjacent to the gap which, on electrical activation according to a predetermined scheme or a predetermined function, undergo an essentially radial change in length in the direction of the gap ( 4 ′), such that the mechanical energy provided by the actuators is transmitted to the fluid medium as flow energy, wherein the flow energy of the fluid medium is transmitted to the rotor and transformed into a rotating drive movement of the rotor ( 2 ; 5 ; 7 ), characterized in that the rotor ( 2 ; 5 ; 7 ) is supported in the stator using a hydrodynamic bearing system, wherein the gap ( 4 ′) forms part of the gap ( 4 ) of the hydrodynamic bearing system and the hydrodynamic bearing comprises a grooved pattern on its bearing surfaces for building up a hydrodynamic pressure within the bearing gap when the rotor is rotated.