Patent ID: 8015665

Claim:
A spring hinge comprises a frame leaf, door leaf, upper and lower tube sections to fixedly connect with frame leaf, and the middle tube section to fixedly connect with door leaf, wherein middle tube section is internally made with a hydraulic damping speed reducing device which is characterized in that the lower tube section is internally installed with a torsion spring device comprising a torsion spring and its spring seat as well as spindle rod, wherein torsion spring being completely sleeved on the exterior of spindle rod is affixed to the spring seat at the lower end thereof, and an upper and lower clutching device is installed between middle tube section and torsion spring device thereby allowing middle tube section and torsion spring device to be separated or combinedly moved, wherein the upper and lower clutching device comprises the axially installed upper clutch seat, middle clutch seat, and lower clutch seat, wherein upper clutch seat is fixedly connected with oil seal of middle tube section at one end thereof, wherein middle clutch seat is radially symmetrically made with two ball holes, and each hole contains two matching steel balls, the sum of diameters of the two steel balls is larger than the thickness of middle clutch seat, and ball cavities are disposed, respectively, in between the upper clutch seat and the middle clutch seat, as well as in between the lower clutch seat and the middle clutch seat, to match with steel balls thereon, while depth of ball cavity is smaller than radius of steel ball; further, upper clutch seat is fixedly connected with middle tube section, wherein middle clutch seat and lower clutch seat are sleeved on spindle rod, and middle clutch seat is fixedly connected with spindle rod while lower clutch seat is movably connected with spindle rod.