Automatic door opening mechanism

An automatic door opening mechanism, for driving an open-close member, and comprising:

• a driving source;
• a transmission assembly, driven by the driving source;
• a screw assembly, comprising a nut and a screw rod threadedly engaged with each other, wherein one end of the screw rod is connected to the open-close member, the screw rod comprises a longitudinal direction and a radial direction perpendicular to the longitudinal direction, and the nut comprises a positioning groove;
• a clutch assembly, disposed between the transmission assembly and the screw assembly, wherein the nut is engageable with or disengageable from the transmission assembly along the radial direction via the clutch assembly, the clutch assembly comprises a retainer, an interactive structure, a latching structure, and a plurality of rolling balls, each of the rolling balls is movably accommodated in the retainer along the radial direction, the latching structure is disposed encircling along an inner periphery of the transmission assembly, the interactive structure is disposed encircling along an outer periphery of the nut, and the plurality of rolling balls are positioned between the latching structure and the interactive structure;
• and
• a plurality of engaging members, arranged circularly in the positioning groove and positioned along the longitudinal direction by the positioning groove, each of the engaging members comprising at least one inclined plane corresponding to each of the rolling balls;
• wherein, when an external force is applied to the open-close member, the open-close member drives the transmission assembly, the latching structure, and the retainer to move together along the longitudinal direction relative to the screw assembly, and the retainer drives the rolling balls to move to make each of the rolling balls be lifted along the radial direction by the inclined plane.