BI-DIRECTIONAL CLUTCH

摘要

BI- DIRECTIONAL CLUTCH There is disclosed a bi-directional clutch, particularly useful in window shade applications. The bidirectional clutch includes a first or core member and an unwrap spring, that is, a spring having an inside diameter somewhat smaller than the diameter of the core, the spring being wound around the core. The unwrap sprinq has a number of helical turns and spring tangs which extend outwardly past the circumference of the spring and generally perpendicular to the axis of the spring. The spring is controlled by a second control or driving member which, when rotated, applies force to one or the other of the spring tangs to unwrap or loosen the spring, thereby allowing the spring to rotate relative to the core. As the spring rotates, one of the spring tangs abuts a third or driven member. The third or driven member is rotated by the spring, allowing the third member to rotate relative to the first or core member. The third or driven member continues to rotate, relative to the first or core member, until the second, control or driving member stops rotating. However, when the driven member is rotated directly, the spring is locked onto the core member and further rotation of the driven member is prevented. According to a first embodiment of the invention, the spring tangs of the unwrap spring are crossed-over, the second, control or driving member has a U-shaped channel which abuts either of the outer surfaces of the spring tangs as the driving member rotates, and the third or driven member has a rib, located between the spring tangs, which is abutted by the inner surface of the spring tangs to transfer rotation from the driving to driven member. In a second embodiment, the spring tangs of the spring are not crossed-over, the second, control or driving member has a rib located between the inner surface of the spring tangs, and the third or driven member has a U-shaped channel which is moved by the outside surface of the spring tangs to transfer rotation from the driving to driven member. When the bi-directional clutch is used as part of a window shade mechanism, the first or core member is held stationary.by attachment to a bracket which is affixed to a window frame, the third or driven member is fixedly attached to a window shade, and the second,control or driving member is turned in a clockwise or counterclockwise direction by a window chain or cord, to either raise or lower the shade.