| 摘要 |
The invention relates to an electromechanical wheel-brake device (10) for an automobile, comprising an electromotor (34) for driving two planetary gears (16, 18) which are connected in series, and which activate the wheel-brake device (10) through a roller thread drive (74, 82, 84). According to the invention, the planetary gears (16, 18) are provided with a first electromagnetic coupling (38, 40, 52) with which a sun wheel (22) of the second planetary gear (18) can be stopped or rotationally fixed to a sun wheel (20) of the first planetary gear (16), and a second electromagnetic coupling (44, 46, 48, 54), with which an internal-geared wheel (30) of the second planetary gear (18) can be stopped or rotationally fixed to an internal-geared wheel (28) of the first planetary gear (16). The invention has the advantage that by using the electromotor (34) and switching the two couplings (38, 40, 52; 44, 46, 48, 54), the roller screw drive (74, 82, 84) can be driven rapidly in order to overcome an air gap, slowly and with considerable reduction in order to then apply a considerable braking force and rapidly for releasing without changing the direction of rotation of the electromotor (34). For use as a parking brake, both couplings (38, 40, 52; 44, 46, 48, 54) are switched to currentless, hereby blocking the second planetary gear (18) and maintaining an applied braking force when the electromotor (34) is currentless.
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