Slip clutch for roller shade

摘要

A slip cutch for a roller blind that includes a clutch base with a shaft portion, a drive sprocket including a drive tube and rotationally mounted on the clutch base, at least one clutch spring and a roller tube connector. The clutch spring maybe a coil spring frictionally engaged about the shaft portion and positioned between the shaft portion and the drive tube. The spring includes end members that engage the drive tube such that rotation of the drive tube about the shaft portion is resisted by the frictional engagement of the spring about the shaft. The roller tube connector is secured about the drive tube and rotates with the drive tube about the shaft portion. The roller tube connector is free from contact with the clutch spring.

主权项

1. A slip clutch for a roller blind of the type having blind fabric wound upon a roller tube, the slip clutch comprising:
a clutch base, said clutch base including a shaft portion; a drive sprocket rotationally mounted on said clutch base, said drive sprocket engageable with a chain or cord to impart rotational movement to said drive sprocket, said drive sprocket including a drive tube having an interior, said drive tube axially receivable about at least a portion of said shaft portion of said clutch base; a roller tube connector having an interior received about at least a portion of said drive tube such that said roller tube connector and said drive tube generally rotate together about said shaft portion, at least one clutch spring, said clutch spring comprising a coil spring frictionally engagable about said shaft portion of said clutch base and positioned generally between said shaft portion and said drive tube, said clutch spring including end members wherein, either each of said end members are independently engagable with said drive tube or one of said end members is engagable with said drive tube and one of said end members is engagable with said roller tube connector, such that rotation of said drive tube about said shaft portion is initially resisted by the frictional engagement of said clutch spring about said shaft portion; wherein rotational force imparted to said drive sprocket causing either said drive tube or said roller tube connector to apply a force to one of said end members of said clutch spring in a direction that encourages an increase in the diameter of said spring to reduce the frictional engagement of said clutch spring with said shaft portion and to permit rotation of said drive tube and said roller tube connector about said shaft portion, and wherein rotational force applied to said roller tube connector in a direction tending to unwind blind fabric from the roller tube causes said roller tube connector to apply a rotational force to said drive tube causing said drive tube to apply a force to one of said end members of said clutch spring in a direction that encourages an increase in the diameter of said spring to reduce the frictional engagement of said clutch spring with said shaft portion thereby permitting rotation of said drive tube and said roller tube connector about said shaft portion and an unwinding of blind fabric from the roller tube.