Roller blind type swimming-pool cover winder - has shaft-coupled spring, and gear reduction ratio increasing as cover unrolls

摘要

The swimming-pool cover, which is of the roller-blind type, has a roller shaft for the cover sheet, coupled to a drive unit. There is a spring (15), coupled to the shaft (1) via a reduction gear (9-14), with a reduction ratio which is automatically increased as the roller-blind cover is unrolled. The reduction gear may be one with a fixed reduction ratio, its outlet driving a rotatable component (14) eccentrically engaged by a spring which has its other end held stationary. The reduction ratio exceeds the threshold total of the number of turns of the shaft between the rolled and unrolled state, while the spring force is augmented as the cover is unrolled. Virtually equal energy is required for rolling up and unrolling, and this is less than that normally needed for rolling up.