Hinge having the function of auto-shutting

A hinge having a function of auto-shutting used between a display screen and a main body of a foldable electronic product, said hinge comprises:

• a base fixed in said foldable electronic product;
• a bracing structure fixedly connected with a display screen of said foldable electronic product;
• a rotation axle having a connecting part connected with said bracing structure and a shank extending through a central circular hole of said base;
• a spring washer set provided on said shank of said rotation axle to provide pressing force;
• and
• a positioning device provided on said shank of said rotation axle, being composed of a positioning block connected with said base and not rotated together with said rotation axle;
• and a positioning piece rotated together with said rotation axle;
• contact surfaces for said positioning block and said positioning piece being provided with a pair of protruding and recessed engaging structures of different sizes mutual symmetrical by position and composed of a pair of protrusions and a pair of detents, said hinge thus having said function of auto-shutting during folding of said foldable electronic product in connection with said hinge;
• a pair of protruding stubs and recess holes are provided at two lateral sides respectively on said positioning block and said positioning piece of said smaller one of said two engaging structures, said protruding stubs and recess holes are mutually engaged when said protrusions and said detents are mutually engaged;
• centers of said protruding stubs has a distance to a central through hole of said positioning piece which is not larger than a distance from an inner edge of a larger one of said protrusions to said center of said central through hole, this prevents a smaller one of said protrusions from falling into a larger one of said detents during opening said foldable electronic product.