Patent ID: 8302655

Claim:
A spring drive device adapted for use in a sunshade assembly, the sunshade assembly including a winding shaft, a shade member that is wound on the winding shaft, and a coupling shaft that has a coupling end coaxial to and rotatable with the winding shaft, and an engaging end opposite to the coupling end, and that is formed with a guided path extending longitudinally from the engaging end toward the coupling end, said spring drive device comprising: a shell unit defining a retaining space that extends along an axis, and including an outer side wall; a spring member disposed in said retaining space, and having a first segment that is connected to said shell unit, and a second segment that is inwardly and radially spaced apart from said first segment; and a connecting shaft including a shaft body which has a central part disposed in said retaining space, an outer end extending outwardly of said outer side wall of said shell unit, and an inner end that is longitudinally opposite to said outer end, said shaft body being formed with a positioning section at said inner end, and a guideway which has an initial region that is slidably engaged with said second segment, and which extends longitudinally from said initial region to terminate at a relay region, such that when said shaft body is moved axially along a coupling route in a direction of the axis, said guideway is kept in slidable engagement with said second segment until said relay region reaches said second segment, said shaft body being angularly displaceable relative to the axis between an unlocked position, where said shaft body is permitted to move axially along the coupling route, and a locked position, where the axial movement of said shaft body is arrested, said positioning section of said connecting shaft being adapted to be engageable with the engaging end of the coupling shaft to align the guided path of the coupling shaft with said guideway such that when the axial movement of said shaft body is continued after said relay region reaches said second segment, the guided path is brought to take over the slidable engagement with said second segment from said relay region while the guided path retrieves said coupling route; wherein said shell unit further includes a retaining member disposed on said outer side wall for retaining said outer end of said shaft body at the locked position.