| 摘要 |
Provided are a ball-screw and an electrically driven actuator with the ball-screw, which are each reduced in weight by reducing the wall thickness of a housing and which each have increased reliability obtained by avoiding the striking of a threaded shaft. An electrically driven actuator 1 is provided with a threaded shaft 10 supported so as not to be rotatable relative to a housing 2 and so as to be axially movable. Thread grooves 9, 16 comprise circular arc-shaped thread grooves 9a, 16a and saw tooth-shaped thread grooves 9b, 16b. When a pull load is applied to the threaded shaft 10, the gaps between the circular arc-shaped thread grooves 9a, 16a and balls 19 disappear and gaps appear between the saw tooth-shaped thread grooves 9b, 16b. As a result, the circular arc-shaped thread grooves 16a, 9a and the balls 19 come in angular contact with each other to become a ball-screw state. When an input in the opposite direction is applied, gaps appear between the circular arc-shaped thread grooves 16a, 9a and the balls 19 and the gaps between the saw tooth-shaped thread grooves 16b, 9b disappear. As a result, the saw tooth-shaped thread grooves 16b, 9b come in sliding contact with each other to become a trapezoidal-thread state. |
