Abstract: A hinge apparatus includes an upper body, a lower body, a shaft whose lower end portion is rotatably installed in the lower body, a piston whose outer circumference is slidably installed along the inner surface of the lower body, a rotational/linear motion converter which converts a rotational motion of the shaft into an axial linear motion of the piston, a damping unit provides a damping function selectively where the piston ascends according to return of the door, a torsion spring rotates the shaft in the door closing direction, and a clutch unit for stopping the elastic force due to reverse twisting of the spring or for restoring the elastic force of the spring.

Abstract: A multipurpose hinge apparatus having an automatic return function is provided in which the apparatus is installed between the door and a main body. The apparatus includes a driving mechanism for ascending and descending a piston rod according to opening and closing of the door which is installed in the upper portion of a cylindrical housing. A piston is connected with the piston rod, in which a one-direction check valve is installed in the piston. The piston partitions an upper chamber and a lower chamber and ascends and descends in association with the piston rod. A first oil path communicates with the upper and lower chambers via the lower portion of the piston rod in the central portion of the piston. A compression spring which makes the piston ascend is inserted into the lower chamber. Oil is filled in the chamber.