Patent ID: 8046874

Claim:
An anti-pinching structure for a supporting frame comprising, a connection base; a first fixing base fixedly disposed on the supporting framework and a through hole of the first fixing base having at least a side edge; a cover body fixedly disposed on the first fixing base and having a guide slot; a positioning block disposed between the first fixing base and the cover and slidable along the guide slot; a spindle disposed with at least a flat surface and insertingly disposed on the first fixing base and a side plate of the connection base; a first locking piece embeddedly fixed on the side plate of the connection base and having a round hole for the insertion of the spindle; a second locking piece insertingly disposed on the spindle and a through hole of the second locking piece having at least a side edge; a spring fixing plate insertingly disposed onto the spindle and a through hole of the spring fixing plate having at least a side edge; a sleeve insertingly disposed on the spindle and positioned between the second locking piece and the spring fixing plate; and a torsion spring insertingly disposed on the sleeve and front and rear ends of the torsion spring embeddedly fixed, respectively, on the side plate of the connection base and on the spring fixing plate; wherein the end of the spindle is insertingly disposed with a resilient element and secured with a nut, and the resilient element impels the spring fixing plate and sleeve to prompt the second locking piece to intimately contact with the first locking piece; consequently, when the supporting framework is folded, two protrusions of the second locking piece constrain two protrusions of the first locking piece so as to form a locking status; when the supporting framework is spread from a folded status, the two protrusions of the second locking piece cross the two protrusions of the first locking pieces and thus disengage from the locking status and the torsion spring forms a supporting torsion against the supporting framework; when the supporting framework is rotated to a positioning point, the positioning block is pushed by a pushing spring and thus the tip portion of the positioning block is inserted into the positioning hole of the side plate so as to prevent the supporting framework from springing back.