| 摘要 |
PROBLEM TO BE SOLVED: To realize a structure in which a braking force attained is high and an electricity consumption at the time of operation of a parking brake can be restricted low.SOLUTION: An electrically-driven actuator of this invention comprises a pressing unit 20, a belleville spring 21, an energizing unit 22 and an energizing ratio conversion unit 23 in addition to an electric motor 8a. The energizing unit 22 is constituted to include a plurality of levers 29 oscillated around rollers 28 so as to displace a pressing plate 30 constituting the pressing unit 20 in a direction where the pressing plate 30 is protruded out of a cylinder space 6a. The energizing ratio conversion unit 23 displaces each of the rollers 28 in a peripheral direction of each of the levers 29 so as to cause an energizing ratio between a resilient force of the belleville spring 21 and a force for displacing the pressing unit 20 in a direction protruded out of the cylinder space 6a on the basis of the resilient force to be changed. Under a state in which the maximum braking force is realized, even if an electrical energizing for the electric motor 8a is stopped, the belleville spring 21 continues to press the pressing unit 20. |
